From jones@pyrite.cs.uiowa.edu Fri Apr  1 12:07:45 EST 1994
Article: 738 of alt.sys.pdp8
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From: jones@pyrite.cs.uiowa.edu (Douglas W. Jones,201H MLH,3193350740,3193382879)
Newsgroups: alt.sys.pdp8
Subject: Strange code fragment
Date: 31 Mar 1994 16:58:01 GMT
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I was going over the paper tape reader I picked up from Rockwell's surplus
outlet, and I found, written in pencil on the inside of the plate that
covers the lamp, the following:

    0030 load-addr
    6743 dep
    5031 dep
    0030 load-addr/clear/cont

This looks suspiciously pdp8ish, despite the fact that the reader was
interfaced to a General Radio Peripheral Expander box.  The same lot
of surplus parts contained 3 RK01 drives, though, also with interfaces
from the GR box.  That fits the following reading of what I found:

    .=0030
    DMNT
    JMP .
    $

But if so, what does this little sequence do?  Is it a boot sequence of
some kind?

And finally, did GR build a PDP-8 compatable processor?  The chips on the
interface card that came with my paper tape reader are dated 1972 and 1973.

					Doug Jones
					jones@cs.uiowa.edu


From the_wolf@tmok.uu.ids.net Fri Apr  1 12:08:09 EST 1994
Article: 739 of alt.sys.pdp8
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From: the_wolf@tmok.uu.ids.net (The Wolf)
Newsgroups: alt.sys.pdp8
Subject: pdp-8
Date: 31 Mar 1994 19:49:40 -0600
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I just acquired a pdp-8a420, and I need some help (Which DEC doesn't seem to
care about giving)
 
I need to know where I can get hardware, software, a copy of OS/8, and MAINDEC
papertape diagnostics. Thanks!
 
I don't read this newsgroup, please direct any replies to my Internet address:
the_wolf@tmok.uu.ids.net  . Thank you!


From bqt@Krille.Update.UU.SE Fri Apr  1 12:08:45 EST 1994
Article: 740 of alt.sys.pdp8
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From: bqt@Krille.Update.UU.SE (Johnny Billquist)
Newsgroups: alt.sys.pdp8
Subject: Re: Strange code fragment
Date: 1 Apr 1994 03:01:11 +0200
Organization: Update Computer Club
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In <2nevep$f96@nexus.uiowa.edu> jones@pyrite.cs.uiowa.edu (Douglas W. Jones,201H MLH,3193350740,3193382879) writes:

>I was going over the paper tape reader I picked up from Rockwell's surplus
>outlet, and I found, written in pencil on the inside of the plate that
>covers the lamp, the following:

>    0030 load-addr
>    6743 dep
>    5031 dep
>    0030 load-addr/clear/cont

>This looks suspiciously pdp8ish, despite the fact that the reader was
>interfaced to a General Radio Peripheral Expander box.  The same lot
>of surplus parts contained 3 RK01 drives, though, also with interfaces
>from the GR box.  That fits the following reading of what I found:

>    .=0030
>    DMNT
>    JMP .
>    $

>But if so, what does this little sequence do?  Is it a boot sequence of
>some kind?

Yes, it is the typical RK8-E bootstrap.
It's also the shortest ever bootstrap I've ever seen for
any processor, any device.

I don't think the mnemonic is DMNT for a RK8-E though.

>And finally, did GR build a PDP-8 compatable processor?  The chips on the
>interface card that came with my paper tape reader are dated 1972 and 1973.

No idea about that one.

	Johnny
-- 
Johnny Billquist                  || "I'm on a bus
CS student at Uppsala University  ||  on a psychedelic trip
email: bqt@minsk.docs.uu.se       ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol


From jvaughan@twain.ucs.umass.edu Fri Apr  1 12:09:38 EST 1994
Article: 741 of alt.sys.pdp8
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From: jvaughan@twain.ucs.umass.edu (Jonathan Vaughan)
Newsgroups: alt.sys.pdp8
Subject: Re: Strange code fragment
Date: 1 Apr 1994 08:36:17 -0500
Organization: University of Massachusetts, Amherst
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NNTP-Posting-Host: twain.ucs.umass.edu


In article <2nevep$f96@nexus.uiowa.edu> jones@cs.uiowa.edu wrote:
[excerpted]

>
>    .=0030
>    DMNT
>    JMP .
>    $
>
>But if so, what does this little sequence do?  Is it a boot sequence
of
>some kind?

It is indeed a boot sequence.  I don't have the materials any more, but it
might have worked with RK05 or perhaps the DSD floppy drive (an 8 inch
floppy drive)-- whatever device 74 was on the bus.  Essentially, the 6743
instruction initiates a DMA transfer to memory--because of the clear
pulse, all the address and block registers in the device controller and
DMA controller are set to zero, so it does a read disk block zero to
memory starting at zero, so it overwrites itself.  When the overwrite
occurs, location 30 becomes a skip on done flag (probably 6741), and 31
becomes jmp .-1. When the block read via DMA is finished, the remainder of
the boot sequence now occupies memory locations 000-377, and a more
ambitious bootstrap sequence takes over when the skip condition is met. 

--jvaughan@hamilton.edu


From jones@pyrite.cs.uiowa.edu Fri Apr  1 12:40:11 EST 1994
Article: 742 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!corpgate!news.utdallas.edu!wupost!math.ohio-state.edu!hobbes.physics.uiowa.edu!news.uiowa.edu!news
From: jones@pyrite.cs.uiowa.edu (Douglas W. Jones,201H MLH,3193350740,3193382879)
Newsgroups: alt.sys.pdp8
Subject: Re: Strange code fragment
Date: 1 Apr 1994 15:34:52 GMT
Organization: University of Iowa, Iowa City, IA, USA
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>From article <2nfrp5$nh0@Krille.Update.UU.SE>,
by bqt@Krille.Update.UU.SE (Johnny Billquist):
>
> It's also the shortest ever bootstrap I've ever seen for
> any processor, any device.

As an old Modcomp IV user, it looks about twice as long as the boot
sequence I used to use:

   XXXX reset/deposit/reset/run

Where the value of XXXX that you put on the switch register is something
I forget.  It was the instruction to begin a DMA transfer, and usually,
it was the only value input from the switches (so they were always set
that way, so I don't remember the value).

Reset set the program counter to zero, deposit did the usual deposit of
switches in memory, incrementing the address, the second reset put the
address back to zero, and the run instruction did as expected.  The
reset also reset the device/cylinder/sector registers and the memory
address register, so the net result was to transfer sector zero of
track zero of cylinder zero to memory, overwriting the instruction.  For
reasons I forget, the instruction itself would hang until overwritten.

				Doug Jones
				jones@cs.uiowa.edu


From lasner@sunSITE.unc.edu Fri Apr  1 12:40:53 EST 1994
Article: 743 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!sunSITE!lasner
From: lasner@sunSITE.unc.edu (Charles Lasner)
Newsgroups: alt.sys.pdp8
Subject: Re: Strange code fragment
Date: 1 Apr 1994 17:39:00 GMT
Organization: University of North Carolina, Chapel Hill
Lines: 97
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References: <2nevep$f96@nexus.uiowa.edu>
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In article <2nevep$f96@nexus.uiowa.edu>,
Douglas W. Jones,201H MLH,3193350740,3193382879 <jones@pyrite.cs.uiowa.edu> wrote:
>I was going over the paper tape reader I picked up from Rockwell's surplus
>outlet, and I found, written in pencil on the inside of the plate that
>covers the lamp, the following:
>
>    0030 load-addr
>    6743 dep
>    5031 dep
>    0030 load-addr/clear/cont
>
>This looks suspiciously pdp8ish, despite the fact that the reader was
>interfaced to a General Radio Peripheral Expander box.  The same lot
>of surplus parts contained 3 RK01 drives, though, also with interfaces
>from the GR box.  That fits the following reading of what I found:
>
>    .=0030
>    DMNT
>    JMP .
>    $
>
>But if so, what does this little sequence do?  Is it a boot sequence of
>some kind?
>
>And finally, did GR build a PDP-8 compatable processor?  The chips on the
>interface card that came with my paper tape reader are dated 1972 and 1973.
>
>					Doug Jones
>					jones@cs.uiowa.edu

Not that I've ever seen them, but GR made some compatible add-ons for the
Omnibus.  Apparently the largest package is some sort of electroncs
testbed station, complete with RK8E or possibly a compatible (there were
several RK-compatibles, not all of which were media-compatible!).  I
suspect that some used heavy-duty BRPE punches for numerical control, etc.
The fact that you found some reader stuff goes with that territory, etc.

In fact, I was recently contacted by a current user of one in Georgia who
needed Kermit-12.  They successfully got Kermit up the hard way by remote
download in .IPL format of the binary into the IPL loader.  (See the
Kermit-12 docs if you are unfamiliar with the "printable" IPL encoing
format, etc.)

The sequence you describe is indeed the RK8E bootstrap for the shortest
toggle-in.  It's limited to use on drive 0, but that's the usual case.

(It's a subset of a longer boot to any drive, etc.)

However, the length of boot is not the shortest, nor unique.

The RK01/RK08 uses the same sequence, and that's the source of the DMNT
described in the source code.  These disks are otherwise quite different;
the RK01 only holds half the capacity, but had some nifty features such
as *real* formatting, i.e., the headers aren't rewritten every time you
write!  Also, it's possible to write-protect each sector individually as
opposed to a pack-wide write-lock.  (Although this feature is almost
useless in OS/8 unless you restrict yourself, etc.)

Now, as to the *shortest* sequence:

Someone once built a floppy based on a Xebec controller.  It's not
compatible with anything, but was a joy to program compared to anything
named RXxx.  Most versions used something that held more than the RX01 as
a better single-density, but I think there were also some MFM
variations.  All I can remember is that it went by a 4-digit model
number, etc.

The people who contacted me for the SCSI project wanted to use them for
commercial purposes, but they were no longer available.  So, we instead
created the floppy-only version of the original MDC8 using an SMS
controller for 8" drives (MFM) that is essentially a replacement for the
absolute original Shugart Associates Standard Interface (SASI) board.
The SMS board was so compatible, that it had all of the quirks of the
SASI except it deleted on-board device copy, because it ties up the
interface doing an off-line copy *slower* than a program can direct it to!

Anyway, the aforementioned Xebec system had a smaller-still boot!  The
sequence is:

	*12 {I'm not sure of this!}

	READ

This IOT was "nasty" as it hung the buss until the DMA finished!  Then
the boot continues in 00013 with the just-read-in code!

However, there is a still shorter boot for it!

	*DOESNTMATTER

That's the entire boot!  No, you didn't miss anything!  Just press a boot
button!  It DMA's into the machine either the READ or alternatively the
RIM loader and starts the machine accordingly.

cjl (or, as they *never* did say on Name That Tune: "I can name that song
in zero notes")


From guenther@news.NeoSoft.com Mon Apr  4 12:21:31 EDT 1994
Article: 744 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!corpgate!news.utdallas.edu!chpc.utexas.edu!cs.utexas.edu!swrinde!news.uh.edu!uuneo.neosoft.com!sugar!guenther
From: guenther@news.NeoSoft.com (Ed Guenther)
Newsgroups: alt.sys.pdp8
Subject: pdp-8 Manual Available
Date: 1 Apr 1994 17:46:12 GMT
Organization: NeoSoft Internet Services -- +1 713 684 5969
Lines: 7
Message-ID: <2nhml4$6ah@uuneo.neosoft.com>
NNTP-Posting-Host: sugar.neosoft.com
X-Newsreader: TIN [version 1.2 PL2]

I have a First Edition Paperback  PDP-8 Manual and reference (1967)
If interested, reply here in alt.sys.pdp8
or to guenther@neosoft.com

The manual is in *excellent* condition !


From jones@pyrite.cs.uiowa.edu Mon Apr  4 12:22:02 EDT 1994
Article: 745 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!corpgate!news.utdallas.edu!wupost!math.ohio-state.edu!hobbes.physics.uiowa.edu!news.uiowa.edu!news
From: jones@pyrite.cs.uiowa.edu (Douglas W. Jones,201H MLH,3193350740,3193382879)
Newsgroups: alt.sys.pdp8
Subject: Oiled paper tape
Date: 1 Apr 1994 20:20:35 GMT
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Nobody ever answered my question about oiled tape.  I have a bunch of it,
in oiled black.  Is oiled tape considered bad because oiled yellow tape
is transparent, and thus hard to read in a photoelectric reader, or does
the oil itself cause problems by attacking plastics used in the readers.
Now that I own a photoelectric reader, this matters to me.

					Doug Jones
					jones@cs.uiowa.edu


From frank@rover.uchicago.edu Mon Apr  4 12:22:54 EDT 1994
Article: 746 of alt.sys.pdp8
Newsgroups: alt.sys.pdp8
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From: frank@rover.uchicago.edu (Frank - Hardware Hacker - Borger)
Subject: Re: Oiled paper tape
Message-ID: <1APR199417405101@rover.uchicago.edu>
News-Software: VAX/VMS VNEWS 1.41    
Sender: news@uchinews.uchicago.edu (News System)
Reply-To: frank@rover.uchicago.edu
Organization: Joint Center for Radiation Therapy
References: <2nhvmj$r40@nexus.uiowa.edu>
Date: Fri, 1 Apr 1994 23:40:00 GMT
Lines: 31

In article <2nhvmj$r40@nexus.uiowa.edu>, jones@pyrite.cs.uiowa.edu (Douglas W. Jones,201H MLH,3193350740,3193382879) writes...
>Nobody ever answered my question about oiled tape.  I have a bunch of it,
>in oiled black.  Is oiled tape considered bad because oiled yellow tape
>is transparent, and thus hard to read in a photoelectric reader, or does
>the oil itself cause problems by attacking plastics used in the readers.
>Now that I own a photoelectric reader, this matters to me.

	The DEC PC04/PC05 manual states the following:

	Tape characteristics		Reader: Gray, unoiled, fan-folded**
					Punch: Oiled or unoiled, fanfolded

	** Tape of up to 12% transmittance may be used. Consult DEC for
	   operation of reader with more transparent tape.


	So the question of tranmission is clearly stated, but I can't find
	any other remark concerning why oiled tape is ok in the Punch, but
	NG in the reader. 

	Oil as such is relatively inert, and only parts of the reader it
	comes in contact with wouldn't be hurt. However, oil does collect
	dust, (check the gunk on your car's engine some time.) A lot of
	oil and dust could cloud up the plastic lens over the photo-xistors.


Frank R. Borger - Physicist     ___      "Maybe thith ith Godth way of telling
Michael Reese - U of Chicago   |___      me to thape-up...or maybe God ith angry
Center for Radiation Therapy   | |_) _   with me... or maybe God juth hath a
net: Frank@rover.uchicago.edu    | \|_)  weird thenth of humor." Grimm the dog,
ph: 312-791-8075 fa: 791-2517       |_)  (with his tongue frozen to a fire-plug)


From guenther@news.NeoSoft.com Mon Apr  4 12:23:21 EDT 1994
Article: 747 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!corpgate!news.utdallas.edu!chpc.utexas.edu!cs.utexas.edu!swrinde!news.uh.edu!uuneo.neosoft.com!sugar!guenther
From: guenther@news.NeoSoft.com (Ed Guenther)
Newsgroups: alt.sys.pdp8
Subject: Re: pdp-8 Manual Available
Date: 2 Apr 1994 14:02:49 GMT
Organization: NeoSoft Internet Services -- +1 713 684 5969
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References: <2nhml4$6ah@uuneo.neosoft.com>
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X-Newsreader: TIN [version 1.2 PL2]

: The manual is in *excellent* condition !
More info on the manual:  It is a "First edition DIGITAL Small
Computer Handbook" for PDP-8, LINC-8, and the "new" PDP-8/S.
Printed in 8/66,  540 pages, soft cover.

Eb .


From dicks@math.ohio-state.edu Wed Apr  6 08:44:47 EDT 1994
Article: 748 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!inxs.concert.net!taco.cc.ncsu.edu!lll-winken.llnl.gov!uwm.edu!math.ohio-state.edu!not-for-mail
From: dicks@math.ohio-state.edu (Ethan Dicks)
Newsgroups: alt.sys.pdp8
Subject: Re: Hi-tech RK05!
Date: 3 Apr 1994 21:22:03 -0400
Organization: Department of Mathematics, The Ohio State University
Lines: 29
Message-ID: <2nnq3r$866@math.mps.ohio-state.edu>
References: <1994Mar30.100236.14667@cc.usu.edu> <2nl76t$def@krille.update.uu.se>
NNTP-Posting-Host: math.mps.ohio-state.edu

In article <2nl76t$def@krille.update.uu.se>,
Johnny Billquist <bqt@Krille.Update.UU.SE> wrote:
>In <1994Mar30.100236.14667@cc.usu.edu> ivie@cc.usu.edu writes:
>
>>In the latest "Processor", I saw an ad for a device that replaces several types
>>of disk drives with a chunk of RAM. It's supposed to be plug-compatible; i.e.,
>>unplug the drive and plug this thing in its place.
>
>>Among the drives it claims to replace is the RK05.
>
>I would think this is only for the pdp11.
>There is a difference between the pdp8 and pdp11 RK05,
>the number of sectors/track...
>
>But who knows, if they are knowing enough, they might have
>been smart enough to allow both types.

The number of bits/track is identical, so it might be possible.  If anyone
sees the ad, please post the company's number.  I'd like to follow up on
this.

-ethan


-- 
This message was (fortunately) not brought to you by Intel...
  "Intel: bringing you the "backward" in backward compatibilty."

dicks@math.ohio-state.edu -or- erd@kumiss.cmhnet.org


From ahhurst@mmm.com Wed Apr  6 08:45:23 EDT 1994
Article: 749 of alt.sys.pdp8
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From: us048503@cc016.mmm.com us048503 (Art Hurst)
Newsgroups: alt.sys.pdp8
Subject: Re: Oiled paper tape
Date: 4 Apr 1994 17:28:25 GMT
Organization: 3M - St. Paul, MN  55144-1000 US
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	If I recall correctly, the oiled tape helped lubricate the punch
	pins on the asr33 tty. Also the high speed paper punches worked
	better with lubrication. We used yellow oiled paper tape in the
	late '60's on an optical reader with no problems. The
	application was an automatic circuit tester that was programmed
	by the paper tape. I believe it was a Remex reader. We also used
	that reader as input to a PDP-8. 

--
Art Hurst                                         Email: ahhurst@mmm.com
3M Company                                        Phone: (805)388-4170
Digital Storage Products Division                 FAX:   (805)388-4804
Camarillo CA 93012


From steveq@swifty.dap.CSIRO.AU Wed Apr  6 08:45:48 EDT 1994
Article: 750 of alt.sys.pdp8
Newsgroups: alt.sys.pdp8
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From: steveq@swifty.dap.CSIRO.AU (Stephen Quigg)
Subject: Re: paper tape
Message-ID: <CnECEM.9nx@syd.dms.CSIRO.AU>
Sender: news@syd.dms.CSIRO.AU
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References: <2mnets$juh@bigblue.oit.unc.edu> <3299@epochsys.UUCP> <2n50u8$fbu@usenet.rpi.edu>
Date: Mon, 28 Mar 1994 22:42:21 GMT
Lines: 18

In article <2n50u8$fbu@usenet.rpi.edu>,
John Wilson <wilsonj@alum01.its.rpi.edu> wrote:
>Inmac used to sell the mylar stuff.  They had quite a fine paper tape
>section in the catalog, back when there was a market for it.  I never
>felt the need to order any, my 8/E came with 11.9 miles of DEC paper tape!
>
>John
>

 Let's see now... 11.9 x 5280 x 12 x 10 = 7539840. That's 7.53 Mbytes!!

   To read on  ASR33 @ 10 cps = 753984 seconds = 8.72 days!
  High speed reader @ 300 cps = 25123  seconds = 0.3  days  (7 hours).

No wonder someone invented disks!

Cheers,
Steve Quigg.


From ivie@cc.usu.edu Wed Apr  6 08:46:24 EDT 1994
Article: 751 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!inxs.concert.net!taco.cc.ncsu.edu!lll-winken.llnl.gov!uwm.edu!cs.utexas.edu!howland.reston.ans.net!agate!dog.ee.lbl.gov!hellgate.utah.edu!cc.usu.edu!ivie
From: ivie@cc.usu.edu
Newsgroups: alt.sys.pdp8
Subject: Re: Hi-tech RK05!
Message-ID: <1994Apr4.235417.15107@cc.usu.edu>
Date: 4 Apr 94 23:54:17 MDT
References: <1994Mar30.100236.14667@cc.usu.edu> <2nl76t$def@krille.update.uu.se> <2nnq3r$866@math.mps.ohio-state.edu>
Organization: Utah State University
Lines: 16

In article <2nnq3r$866@math.mps.ohio-state.edu>, dicks@math.ohio-state.edu (Ethan Dicks) writes:
> The number of bits/track is identical, so it might be possible.  If anyone
> sees the ad, please post the company's number.  I'd like to follow up on
> this.

Vermont Research Corporation
Precision Park, N. Springfield, VT 05150
(802)886-2256 Fax: (802)886-2682

The ad says they can replace Diablo, CDC Hawk, Pertec, Ampex, RK05,
and Wangco drives, with the promise of SMD, Drum, and Core if you're
really interested. The picture clearly states "Solid State Disk".
-- 
----------------+------------------------------------------------------
Roger Ivie      | Don't think of it as a 'new' computer, think of it as
ivie@cc.usu.edu |     'obsolete-ready'


From bqt@Krille.Update.UU.SE Wed Apr  6 08:46:42 EDT 1994
Article: 752 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!news-feed-2.peachnet.edu!news-feed-1.peachnet.edu!darwin.sura.net!howland.reston.ans.net!pipex!sunic!columba.udac.uu.se!Krille.Update.UU.SE!Krille.Update.UU.SE!not-for-mail
From: bqt@Krille.Update.UU.SE (Johnny Billquist)
Newsgroups: alt.sys.pdp8
Subject: Re: Hi-tech RK05!
Date: 3 Apr 1994 03:46:55 +0200
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In <1994Mar30.100236.14667@cc.usu.edu> ivie@cc.usu.edu writes:

>In the latest "Processor", I saw an ad for a device that replaces several types
>of disk drives with a chunk of RAM. It's supposed to be plug-compatible; i.e.,
>unplug the drive and plug this thing in its place.

>Among the drives it claims to replace is the RK05.

I would think this is only for the pdp11.
There is a difference between the pdp8 and pdp11 RK05,
the number of sectors/track...

But who knows, if they are knowing enough, they might have
been smart enough to allow both types.

	Johnny
-- 
Johnny Billquist                  || "I'm on a bus
CS student at Uppsala University  ||  on a psychedelic trip
email: bqt@minsk.docs.uu.se       ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol


From wilsonj@alum01.its.rpi.edu Wed Apr  6 21:48:31 EDT 1994
Article: 753 of alt.sys.pdp8
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From: wilsonj@alum01.its.rpi.edu (John Wilson)
Newsgroups: alt.sys.pdp8
Subject: Re: Hi-tech RK05!
Date: 4 Apr 1994 02:41:05 GMT
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I saw the ad too, but I'm 150 miles from my Processor right now...
If I remember correctly the company was in VT (802 area code), for some reason
I think they were in the Brattleboro area (or maybe it was Springfield???).

Nice to see VT starting to produce some neat stuff, if this keeps up maybe I'll
actually be able to find a decent job and move back to the land of not being
required to register to vote for a particular party, and of not having to turn
in your plates when you take the insurance off your car while you're rebuilding
it...


From jones@pyrite.cs.uiowa.edu Thu Apr  7 10:54:25 EDT 1994
Article: 754 of alt.sys.pdp8
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From: jones@pyrite.cs.uiowa.edu (Douglas W. Jones,201H MLH,3193350740,3193382879)
Newsgroups: alt.sys.pdp8
Subject: Paper tape reader/punch documentation
Date: 6 Apr 1994 16:11:30 GMT
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In searching for documentation for my newly acquired IOMEC/Digitronics
model 2540 paper tape reader, I came up with original documentation for
other Digitronics models.  If anyone has one of the following, I now
have the manual, including schematics, parts lists and manuafcturer's
maintenance recommendations, in good condition:

	Digitronics model 2060 paper tape reader.
		This is a 1968 vintage 60 cps reader, with a solenoid
		and ratchet mechanism to move the tape past the read
		station, and a read-station using electrical contact
		balls to feel for the holes.

	Digitronics model 2500 paper tape reader.
		This is a 1967 vintage 300 cps reader, with a
		photoelectric read station, a tubular lamp, a capstan
		drive, solenoid operated pinch roller to advance the
		tape, and friction brake to stop the tape.

	Digitronics model 1560 punch.
		This is a 1968 vintage 60 cps punch, with the
		same dual solenoid ratchet mechanism as the 2060 reader
		to move the tape, and direct solenoid drive of the
		hammers for each punch pin.

So, while I'm still looking for documentation on my 2540 reader, I have
found documents for related machines that may be of some use to others.
The model 2500 is the direct ancestor of my model 2540 reader, and some
of the subassemblies are the same.  Where there are differences, it
looks like the new model is a real improvement (such things as using a
standard truck lamp instead of a difficult to find tubular lamp, or
replacing a belt drive on the capstan with a direct drive).  The interface
electronics are completely different, however.

				Doug Jones
				jones@cs.uiowa.edu


From lasner@sunSITE.unc.edu Fri Apr  8 11:41:23 EDT 1994
Article: 755 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!sunSITE!lasner
From: lasner@sunSITE.unc.edu (Charles Lasner)
Newsgroups: comp.sys.dec.micro,alt.sys.pdp8
Subject: Re: RX50 and Pro's - two questions
Date: 8 Apr 1994 04:22:09 GMT
Organization: University of North Carolina, Chapel Hill
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References: <CnnIt4.Hzu@sed.csc.com> <CnqqG7.2M1@watdragon.uwaterloo.ca> <2nuc55$hh4@bigblue.oit.unc.edu> <CnwBv6.5nJ@watdragon.uwaterloo.ca>
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In article <CnwBv6.5nJ@watdragon.uwaterloo.ca>,
Ken Wellsch <kcwellsc@watdragon.uwaterloo.ca> wrote:
>>> You also need the added magic header numbers at the start of
>>> the boot block to be recognised as a boot block.
>>
>> Can you give specifics about the magic numbers required for bootability,
>> and/or a DEC spec for what it's called?
>
>Here is where I first encountered these magic numbers
>(from the 2.9BSD port to the Pro):
>
> / eight dummy words to keep DEC firmware happy
> / must be prepended onto any boot block
>	0
>	405
>	0
>	67
>	0
>	42020
>	105041
>	400
>
>Which using the document "CTI Bus: Technical Manual" (alas which also says,
>"confidential information" so hopefully I'm not going to catch heck on this)
>translates to (in octal still):
>
>  byte  0	0	Type 2 or 4 boot block
>  byte  1	0	Type 1, 2 or 3 boot block
>  byte  2	5	Offset from 0 to identification area, in words
>  byte  3	1	System volume
>  byte  4	0	not used here
>  byte  5	0	not used here
>
>  byte  6	0	I don't know what these four are about
>  byte  7	67	since the offset above jumps over them.
>  byte  8	0
>  byte  9	0
>
>  byte 10	20	CPU type, 020 = PDP-11
>  byte 11	104	Controller type, 104 = non-MSCP CTI bus controller
>
>  byte 12	41	File structure, 041 = Files-11 Level 1
>  byte 13	212	Checksum
>
>  byte 14	0	just says 0
>  byte 15	1	Version number of standard,
>			001 = initial version, one-sided.
>
>So I guess someone just took the header of some stock DEC diskette
>and used that if I've not been mistaken in my translation.

Thanks for piecing together *exactly* what I'm referring to!

In the DECmate II/III/III+ world, we are obliged to conform to this same
nonsense.  In order for either a hard disk volume or a diskette to be
considered bootable, the following tests are made in the DECmate ROM:

1)	Byte[0]-Byte[1] .EQU. 000  {This seems consistent with your
description although I have no idea what the variations would be, etc.}

2)	Byte[2] is an index into the record as to where to find the rest
of the stuff.  Multiply by 2 to get the byte number to start looking at.
In the case of hard disk volumes, this value is 3; in the case of
diskettes, it's 2.  So, for a typical diskette, this means look in byte
4.  The actual ROM code starts looking in byte 6-9.  If the test fails,
it then starts over in byte 4-7.  If both variants flunk, the machine has
no boot device.

3)	Assuming the hard disk case, look at byte[6] and byte[7].  Both
values have to have a certain bit on (in octal):

	byte[6] .AND. byte[7] .AND. 010 .EQU. 010  has to be true.  I'm
not quite sure why, but this is a DECmate, not an -11 family member!

	byte[6] + byte[7] + byte[8] + byte[9] .EQU. 377 in 8-bit
arithmetic has to be true.

	If any part of test 3) flunks, go back to byte[4] and try again.
If 4-7 can't hack it either, the boot flunks, and you get a big blinking
floppy on the screen until you change to a bootable one, etc.

Other bytes are set to other values, but they aren't checked for in the
DECmate ROM.

All of this would be a minor nuisance on the DECmates, but in fact it's a
major hassle!

PDP-8 convention is that the boot is performed by reading in track 1,
sector 1 into location 00002 and following until the boot code gets
overlayed by what came in, which in turn determines what happens next,
etc.  This all derives from the fact that all PDP-8 RX hardware
(01/02/03/50) programs the same exact way other than a few minor quirks
and the overall disk geometry (77 tracks, 80 tracks; 10 sectors, 26
sectors, etc.)

So, what this *should* have meant is that the 6120 code is merely
hampered by the fact that logical record 0000 has an 8-word "hole" in it
at the beginning, so that the code that loads is a bit smaller than
usual.  Thus, the system startup code has to be a bit tighter, etc.
Annoying, but not fatal, etc.

However, what *does* happen *is* fatal!

OS/8 family convention is that it's totally normal to expect to be able
to call a device handler and have any logical record written or read with
no restriction.  Indeed, certain standard utilities set out to read,
modify, write back record 0000 as a normal mundane system operation, etc.

But on the DECmates, this *DESTROYS* the system!!!

Some band-aids have been applied to partially inhibit these otherwise
normal operations, but they aren't completely effective, not to mention
the loss of the underlying utility of the operations, etc.  (The system
BUILD utility can't be run for example!)

I have traced the problem down to the basics:

On the PDP-8, the norm is to use the RX01/02 12-bit mode.  (-11
controllers never set this bit on the RX buss, but it's always there.)
From the PDP-8 perspective, the RX01 is a device with 8-bit and 12-bit,
and the RX02 is a device with 16-bit and 12-bit.  If you are using
single-density diskettes, the 12-bit mode is totally compatible.  If you
are using byte mode, the RX02 must include 16-bit command transfer by
sending an extra byte after the TR flag raises.  This must NOT be
performed on the RX01 in byte mode.  (Note: there are RT-11 handlers for
an RX02 on an RX01's controller that do the same thing.)

So, it comes as no surprise that the DECmates boot up in 12-bit mode,
i.e., the contents of track 1, sector 1 are read into 00002 and following
in 12-bit mode.  The system that comes in contains 12-bit mode data that
overlays the 12-bit words in 12-bit memory  The 12-bit-oriented contents
(ignoring the 25% additional data that's actually on the diskette)
represent part of the normal read/write addressable data space the
handlers see, etc.

But on the DECmate, the organization of the data is different from
RX01/02 where this would be no problem.  On the RX01/02, the 12-bit data
is in the form of 12-bit bytes, i.e., the same stream of bits that all
others see as 8-bit bytes laid end to end in order.  Since this is a
12-bit mode transfer, the sector data ceases when the first 3/4 of the
data is transferred to/from the -8.  (So, on the RX01, the -8 transfers
64 12-bit words that are the same exact data as the first 96 bytes of the
sector.  The last 32 bytes of data aren't involved with the -8.  In point
of fact, I believe that what's written is a replication of the last 8
bits the -8 did transfer, etc.  For an RX02, double all the numbers, but
the same factors apply, etc.)

On the DECmate RX50 and also identically on the hard disk controller, the
data is instead organized as 16-bit data.  Thus, relative to byte mode
transfer, the even bytes are taken from the low-order PDP-8 12-bit word's
8 bits and are all present.  But the odd byte is taken from the
high-order PDP-8 12-bit word's 4 bits.  The "unused" bits are filled in
with 0000!

Thus, unlike the RX01/02 where the unused data happens all together at
the end of the record, the RX50 (and RD51) "shred" the data every 16 bits.

Unluckily, this means that the checksum byte's low-order bits get zeroed
every time the record is written in 12-bit mode!

Thus, we have a ludicrous problem:  we have a convention where we have to
read in the record in 12-bit mode, reckon it in 12-bit mode, but we
aren't allowed to write it in 12-bit mode!  To even create this record,
you have to write a kludge where you pre-translate the data into 8-bit
bytes as they look in byte mode but yet are actually 12-bit words to be
later read in when the boot read is performed in 12-bit mode!  (Note: I
have found those very utilities; they kludged OS/278 PIP to do a
special-case check for RX50.  However, there is no equivalent for the
hard disk.  To attempt to change a system head there is fatal!)

Actually, I have defined a way out of this mess: By re-arranging the four
bytes involved in the checksum, I can make the even byte before the
checksum contain the proper checksum that gets preserved (because it's an
even byte).  The odd byte (formerly the checksum) now contains a value
whose 4 bits are meant to be 0000 whether written that way in byte mode
or become that way in 12-bit "shred" mode.  This involves a one-word
(12-bits) patch to the handler that *can* be performed in 12-bit mode
using any number of utilities (doing it the way it was meant to be!).
Once done, both the hard disk and diskette volumes work fine!

My question is: does my non-standard value actually "matter"?  Will the
avenging god of DEC boot standards visit me in the night for having
modified their sacred magic numbers?  (So ill-ly conceived for the
DECmate, but "standard"!)

If such a disk is used on any utility anyone here can think of on any
machine, does any program actually care?

IF the answer is "yea, verily" then I can write an "export" utility that
puts the disk back to the original value.  (And should any of the
standard utilities operate on it, it becomes non-bootable!  However,
using the corresponding "import" utility would restore it to
boot-worthiness, etc.)

Perhaps someone can find a more "master" reference to where all of this
nonsense started, etc.

The answer to the question will allow further work to happen on fixing
the O/S; the released version is broken as I stated above, etc.

cjl (watching the skies for boot-block warlords)


From jones@cs.uiowa.edu Fri Apr  8 11:59:17 EDT 1994
Article: 756 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!news.duke.edu!MathWorks.Com!europa.eng.gtefsd.com!howland.reston.ans.net!math.ohio-state.edu!hobbes.physics.uiowa.edu!news.uiowa.edu!news
From: jones@cs.uiowa.edu (Douglas W. Jones)
Newsgroups: alt.sys.pdp8,alt.answers,news.answers
Subject: PDP-8 Frequently Asked Questions (posted every other month)
Followup-To: alt.sys.pdp8
Date: 8 Apr 94 08:08:08 GMT
Organization: Computer Science, University of Iowa, Iowa City, Iowa, USA
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Summary: Answers to common questions about antique DEC PDP-8 computers.
	Those posting to alt.sys.pdp8 should read this.
Keywords: FAQ DEC PDP 8
Xref: bigblue.oit.unc.edu alt.sys.pdp8:756 alt.answers:2276 news.answers:19454

Archive-name: dec-faq/pdp8
Last-modified: Apr 7, 1994

This version of the alt.sys.pdp8 FAQ has been modified to conform to
RFC1153 USENET digest format (with exceptions due to the fact that it
is not really a digest).  This should aid in automatic conversion of
this material to HTML and other interesting formats.
	
Contents:

	What is this FAQ?
	What is a PDP?
	What is a PDP-8?
	What is the PDP-8 instruction set?
	What does PDP-8 assembly language look like?
	What character sets does the PDP-8 support?
	What different PDP-8 models were made?
	What about the LINC-8 and PDP-12?
	Where can I get a PDP-8 today?
	Where can I get PDP-8 documentation?
	What operating systems were written for the PDP-8?
	What programming languages were supported on the PDP-8?
	Where can I get PDP-8 software?
	Where can I get additional information?
	What use is a PDP-8 today?
	Who's Who?

----------------------------------------------------------------------

Subject: What is this FAQ?

Frequently Asked Questions about the DEC PDP-8 computer.

	By Douglas Jones, jones@cs.uiowa.edu
	(with help from many folks)

The most recent version of this file is available by anonymous FTP from:

	ftp://rtfm.mit.edu/pub/usenet/alt.sys.pdp8
	ftp://sunsite.unc.edu/pub/academic/computer-science/history/pdp-8/docs

An obsolete version of this file is available on the Walnut Creek CDrom.

------------------------------

Subject: What is a PDP?

In 1957, Ken Olson and Harlan Anderson founded Digital Equipment
Corporation (DEC), capitalized at $100,000, and 70% owned by American
Research and Development Corporation.  The founders wanted to call the
company Digital Computer Corporation, but the venture capitalists
insisted that they avoid the term Computer and hold off on building
computers.  With facilities in an old woolen mill in Maynard
Massachusetts, DEC's first product was a line of transistorized digital
"systems modules", plug-in circuit boards with a few logic gates per
board.  Starting in 1960, DEC finally began to sell computers (the
formal acceptance of the first PDP-1 by BBN is reported in Computers
and Automation, April 1961, page 8B).  Soon after this, there were
enough users that DECUS, the Digital Equipment Computer User's Society
was founded.

DEC's first computer, the PDP-1, sold for only $120,000 at a time when
other computers sold for over $1,000,000.  (A good photo of a PDP-1 is
printed in Computers and Automation, Dec. 1961, page 27).  DEC quoted
prices as low as $85,000 for minimal models.  The venture capitalist's
insistance on avoiding the term computer was based on the stereotype
that computers were big and expensive, needing a computer center and a
large staff; by using the term Programmable Data Processor, or PDP, DEC
avoided this stereotype.  For over a decade, all digital computers sold
by DEC were called PDPs.  (In early DEC documentation, plural form
"PDPs" is used as a generic term for all DEC computers.)

In the early 1960's, DEC was the only manufacturer of large computers
without a leasing plan.  IBM, Burroughs, CDC and other computer
manufacturers leased most of their machines, and many machines were
never offered for outright sale.  DEC's cash sales approach led to the
growth of third party computer leasing companies such as DELOS, a
spinoff of BB&N.

DEC built a number of different computers under the PDP label, with a
huge range of price and performance.  The largest of these are fully
worthy of large computer centers with big support staffs.  Many early
DEC computers were not really built by DEC.  With the PDP-3 and LINC,
for example, customers built the machines using DEC parts and
facilities.  Here is the list of PDP computers:

    MODEL  DATE  PRICE     BITS  COMMENTS
    =====  ====  ========  ====  =====
    PDP-1  1960  $120,000  18    DEC's first computer
    PDP-2            NA    24    Never built?
    PDP-3            NA    36    One built by a customer, not by DEC.
    PDP-4  1962   $60,000  18    Predecessor of the PDP-7.
    PDP-5  1963   $27,000  12    The ancestor of the PDP-8.
    PDP-6  1964  $300,000  36    A big computer; 23 built, most for MIT.
    PDP-7  1965   $72,000  18    Widely used for real-time control.
    PDP-8  1965   $18,500  12    The smallest and least expensive PDP.
    PDP-9  1966   $35,000  18    An upgrade of the PDP-7.
    PDP-10 1967  $110,000  36    A PDP-6 followup, great for timesharing.
    PDP-11 1970   $10,800  16    DEC's first and only 16 bit computer.
    PDP-12 1969   $27,900  12    A PDP-8 relative.
    PDP-13           NA          Bad luck, there was no such machine.
    PDP-14                       A ROM-based programmable controller.
    PDP-15 1970   $16,500  18    A TTL upgrade of the PDP-9.
    PDP-16 1972      NA    8/16  A register-transfer module system.

Corrections and additions to this list are welcome!  The prices given
are for minimal systems in the year the machine was first introduced.
The bits column indicates the word size.  Note that the DEC PDP-10
became the DECSYSTEM-20 as a result of marketing considerations, and
DEC's VAX series of machines began as the Virtual Address eXtension of
the never-produced PDP-11/78.

It is worth mentioning that it is generally accepted that the Data
General Nova (see photo, Computers and Automation, Nov. 1968, page 48)
was originally developed as the PDP-X, a 16-bit multi-register version
of the PDP-8.  A prototype PDP-X was built at DEC before the design was
rejected.  This and a competing 16-bit design were apparently submitted
to Harold McFarland at Carnegie-Mellon University for evaluation;
McFarland (and perhaps Gordon Bell, who was at C-MU at the time)
evaluated the competing designs and rejected both in favor of what we
know as the PDP-11.  One speculative explanation for Bell's rejection
of the design that became the Nova is that the competing proposal was
submitted using register-transfer notation, a notation he had introduced
in "Bell and Newell, Computer Structures -- Readings and Examples".
An alternate version of the story is that the reason that DEC never
produced a PDP-13 was because the number 13 was assigned to what became
the Nova; this is unlikely because the PDP-X prototype came before the
PDP-11.  Both DEC and Data General are quiet about these stories.

Today, all of the PDP machines are in DEC's corporate past, with the
exception of the PDP-11 family of mini and microcomputers.

Of course, occasionally, some lab builds a machine out of DEC hardware
and calls it a PDP with a new number.  For example, the Australian
Atomic Energy Commission once upgraded a PDP-7 by adding a PDP-15 on
the side; they called the result a PDP-22.

------------------------------

Subject: What is a PDP-8?

The PDP-8 family of minicomputers were built by Digital Equipment
Corporation between 1965 and 1990, although it is worth noting that the
term minicomputer first came into prominence in early 1968 (See the
Interdata ad in Computers and Automation, May 1968, page 10).  The PDP-8
was largely upward compatable with the PDP-5, a machine that was
unveiled on August 11, 1963 at WESCON, and the inspiration for that
machine came from two earlier machines, the LINC and the CDC 160.  All
of these machines were characterized by a 12 bit word with no hardware
byte structure, a 4K minimum memory configuration, and simple but
powerful instruction sets.

Although some people consider the CDC 160 the first minicomputer, the
PDP-8 was the definitive minicomputer.  By late 1973, the PDP-8 family
was the best selling computer in the world, and it is likely that it was
only displaced from this honor by the Apple II (which was displaced by
the IBM PC).  Most models of the PDP-8 set new records as the least
expensive computer on the market at the time of their introduction.
The PDP-8 has been described as the model-T of the computer industry
because it was the first computer to be mass produced at a cost that
just about anyone could afford.

C. Gordon Bell has said that the basic idea of the PDP-8 was not really
original with him.  He gives credit to Seymour Cray (of CDC and later
Cray) for the idea of a single-accumulator 12 bit minicomputer.  Cray's
CDC 160 family (see CACM, march 1961, photo on page 244, text on page
246) was such a machine, and in addition to the hundreds of CDC 160
systems sold as stand-alone machines, a derivative 12 bit architecture
was used for the I/O processors on Cray's first great supercomputer,
the CDC 6600.

Note that Cray's 12 bit machines had 6 basic addressing modes with
variable length instruction words and other features that were far from
the simple elegance of the PDP-8.  Despite its many modes, the CDC
architecture lacked the notion of current page addressing, and the
result is that, for examples that don't involve indexing, PDP-8 code is
generally as tight as the code on Cray's machines.

------------------------------

Subject: What is the PDP-8 instruction set?

The PDP-8 word size is 12 bits, and the basic memory is 4K words.  The
minimal CPU contained the following registers:

	PC - the program counter, 12 bits.
	AC - the accumulator, 12 bits.
	L  - the link, 1 bit, commonly prefixed to AC as <L,AC>.

It is worth noting that many operations such as procedure linkage and
indexing, which are usually thought of as involving registers, are done
with memory on the PDP-8 family.

Instruction words are organized as follows:
	 _ _ _ _ _ _ _ _ _ _ _ _
	|_|_|_|_|_|_|_|_|_|_|_|_|
	|     | | |             |
	|  op |i|z|    addr     |

	op   - the opcode.
	i    - the indirect bit (0 = direct, 1 = indirect).
	z    - the page bit (0 = page zero, 1 = current page).
	addr - the word in page.

The top 5 bits of the 12 bit program counter give the current page, and
memory addressing is also complicated by the fact that absolute memory
locations 8 through 15 are incremented prior to use when used as indirect
addresses.  These locations are called auto-index registers (despite the
fact that they are in memory); they allow the formulation of very tightly
coded array operations.

The basic instructions are:

	000 - AND - and operand with AC.
	001 - TAD - add operand to <L,AC> (a 13 bit value).
	010 - ISZ - increment operand and skip if result is zero.
	011 - DCA - deposit AC in memory and clear AC.
	100 - JMS - jump to subroutine.
	101 - JMP - jump.
	110 - IOT - input/output transfer.
	111 - OPR - microcoded operations.

The ISZ and other skip instructions conditionally skip the next
instruction in sequence.  The ISZ is commonly used to increment a loop
counter and skip if done, and it is also used as an general increment
instruction, either followed by a no-op or in contexts where it is known
that the result will never be zero.

The JMS instruction stores the return address in relative word zero of
the subroutine, with execution starting with relative word one.
Subroutine return is done with an indirect JMP through the return
address.  Subroutines commonly increment their return addresses to index
through inline parameter lists or to perform conditional skips over
instructions following the call.

The IOT instruction has the following form:
	 _ _ _ _ _ _ _ _ _ _ _ _
	|1|1|0|_|_|_|_|_|_|_|_|_|
	|     |           |     |
	|     |   device  | op  |

The IOT instruction specifies one of up to 8 operations on one of 64
devices.  Typically (but not universally), each bit of the op field
evokes an operation, and these can be microcoded in left to right
order.  Prior to the PDP-8/E, there were severe restrictions on the
interpretation of the op field.

As an example of the use of IOT instructions, consider the console
terminal interface.  On early PDP-8 systems, this was always assumed to
be an ASR 33 teletype, complete with low-speed paper tape reader and
punch.  It was addressed as devices 03 (the keyboard/reader) and 04
(the teleprinter/punch):
	 _ _ _ _ _ _ _ _ _ _ _ _
	|1|1|0|_|_|_|_|_|_|_|_|_|
	      |0 0 0 0 1 1|0 0 1  - KSF - keyboard skip if flag
	      |0 0 0 0 1 1|0 1 0  - KCC - keyboard clear flag
	      |0 0 0 0 1 1|1 0 0  - KRS - keyboard read static

The keyboard flag is set by the arrival of a character.  The KCC
instruction clears both the flag and the accumulator.  KRS ors the 8 bit
input data with the low order 8 bits of AC.  The commonly used KRB
instruction is the or of KCC and KRS.  To await one byte of input, use
KSF to poll the flag, then read it with KRB.
	 _ _ _ _ _ _ _ _ _ _ _ _
	|1|1|0|_|_|_|_|_|_|_|_|_|
	      |0 0 0 1 0 0|0 0 1  - TSF - teleprinter skip if flag
	      |0 0 0 1 0 0|0 1 0  - TCF - teleprinter clear flag
	      |0 0 0 1 0 0|1 0 0  - TPC - teleprinter print static

The teleprinter flag is set by the completion of the TPC operation (as
a result, on startup, many applications use TPC to print a null in order
to get things going).  TCF clears the flag, and TPC outputs the low
order 8 bits of the accumulator.  The commonly used TLS instruction is
the or of TCF and TPC.  To output a character, first use TSF to poll the
flag, then write the character with TLS.

IOT instructions may be used to initiate data break transfers from block
devices such as disk or tape.  The term "data break" was, for years,
DEC's preferred term for cycle-stealing direct-memory-access data
transfers.

Some CPU functions are accessed only by IOT instructions.  For example,
interrupt enable and disable are IOT instructions:
	 _ _ _ _ _ _ _ _ _ _ _ _
	|1|1|0|_|_|_|_|_|_|_|_|_|
	      |0 0 0 0 0 0|0 0 1  - ION - interrupts turn on
	      |0 0 0 0 0 0|0 1 0  - IOF - interrupts turn off

An interrupt was requested when any device raised its flag.  The console
master clear switch would reset all flags and disable interrupts.
Effectively, an interrupt is a JMS instruction to location zero, with
the side effect of disabling interrupts.  The interrupt service routine
would test flags and perform the operations needed to reset them, and
then return using ION immediately before the indirect return JMP.  The
effect of ION is delayed so that interrupts are not enabled until after
the JMP.

The instructions controlling the optional memory management unit are
also IOT instructions.  This unit allows the program to address up to
23K of main memory by adding a 3 bit extension to the memory address.
Two extensions are available, one for instruction fetch and direct
addressing, the other for indirect addressing.

A wide variety of operations are available through the OPR microcoded
instructions:
         _ _ _ _ _ _ _ _ _ _ _ _
Group 1 |1|1|1|0|_|_|_|_|_|_|_|_|
	         1                - CLA - clear AC
	           1              - CLL - clear the L bit
                     1            - CMA - ones complement AC
                       1          - CML - complement L bit
                               1  - IAC - increment <L,AC>
                         1 0 0    - RAR - rotate <L,AC> right
                         0 1 0    - RAL - rotate <L,AC> left
	                 1 0 1    - RTR - rotate <L,AC> right twice
	                 0 1 1    - RTL - rotate <L,AC> left twice

In general, the above operations can be combined by oring the bit
patterns for the desired operations into a single instruction.  If none
of the bits are set, the result is the NOP instruction.  When these
operations are combined, they operate top to bottom in the order shown
above.  The exception to this is that IAC cannot be combined with the
rotate operations on some models, and attempts to combine rotate
operations have different effects from one model to another (for example,
on the PDP-8/E, the rotate code 001 means swap 6 bit bytes in the
accumulator, while previous models took this to mean something like
"shift neither left nor right 2 bits").
         _ _ _ _ _ _ _ _ _ _ _ _
Group 2 |1|1|1|1|_|_|_|_|_|_|_|0|
                   1     0        - SMA - skip on AC < 0  \
                     1   0        - SZA - skip on AC = 0   > or group
                       1 0        - SNL - skip on L /= 0  /
                   0 0 0 1        - SKP - skip unconditionally
                   1     1        - SPA - skip on AC >= 0 \
                     1   1        - SNA - skip on AC /= 0  > and group
                       1 1        - SZL - skip on L = 0   /
                 1                - CLA - clear AC
                           1      - OSR - or switches with AC
                             1    - HLT - halt

The above operations may be combined by oring them together, except that
there are two distinct incompatible groups of skip instructions.  When
combined, SMA, SZA and SNL, skip if one or the other of the indicated
conditions are true (logical or), while SPA, SNA and SZL skip if all of
the indicated conditions are true (logical and).  When combined, these
operate top to bottom in the order shown; thus, the accumulator may be
tested and then cleared.  Setting the halt bit in a skip instruction is
a crude but useful way to set a breakpoint for front-panel debugging.
If none of the bits are set, the result is an alternative form of no-op.

A third group of operate microinstructions (with a 1 in the least
significant bit) deals with the optional extended arithmetic element to
allow such things as hardware multiply and divide, 24 bit shift
operations, and normalize.  These operations involve an additional data
register, MQ or multiplier quotient, and a small step count register.
On the PDP-8/E and successors, MQ and the instructions for loading and
storing it were always present, even when the EAE was absent, and the
EAE was extended to provide a useful variety of 24 bit arithmetic
operations.

------------------------------

Subject: What does PDP-8 assembly language look like?

There are many different assemblers for the PDP-8, but most use a
compatable basic syntax; here is an example:

	START,	CLA CLL		/ Clear everything
		TAD	X	/ Load X
		AND I	Y	/ And with the value pointed to by Y
		DCA	X	/ Store in X
		HLT		/ Halt

	X,	1 		/ A variable
	Y,	7 		/ A pointer

Note that labels are terminated by a comma, and comments are separated
from the code by a slash.  There are no fixed fields or column
restrictions.  The "CLA CLL" instruction on the first line is an example
of the microcoding of two of the Group 1 operate instructions.  CLA
alone has the code 7200 (octal), while CLL has the code 7100; combining
these as "CLA CLL" produces 7300.  As a general rule, except when memory
reference instructions are involved, the assembler simply ors together
the values of all blank separated fields between the label and comment.
	
Indirection is indicated by the special symbol I in the operand field,
as in the third line of the example.  The typical PDP-8 assembler has no
explicit notation to distinguish between page zero and current page
addresses.  Instead, the assembler is expected to note the page holding
the operand and automatically generate the appropriate mode.  If the
operand is neither in the current page nor page zero, some assemblers
will raise an error, others will automatically generate an indirect
pointer to the off-page operand (This feature should be avoided!).

Note, in the final two lines of the example, that there is no "define
constant" pseudo-operation.  Instead, where a constant is to be
assembled into memory, the constant takes the place of the op-code field.

The PDP-8 has no immediate addressing mode, but most assemblers provide
a notation to allow the programmer to ignore this lack:

		TAD	(3)	/ add 3, from memory on the current page.
		TAD	[5]	/ add 5, from memory on page zero.
		JMP I	(LAB)	/ jump indirect through the address of LAB.

Assemblers that support this automatically fill the end of each page
with constants defined in this way that have been accumulated during the
assembly of that page.  Note that the variants "(3" and "[5" (with no
closing parentheses) are usually allowed but the use of this sloppy form
is discouraged.  Furthermore, the widely used PAL8 assembler interprets
"(3)+1" as being the same as "(3+1)".

Arithmetic is allowed in operand fields and constant definitions, with
expressions evaluated in strict left-to-right order, as:

		TAD	X+1	/ add the contents of the location after X.
		TAD	(X-1)	/ add the address of the location before X.

Other operators allowed included and (&), or (!), multiply (^) and divide
(%), as well as a unary sign (+ or -).  Unfortunately, one of the most
widely used assemblers, PAL8, has trouble when unary operators are mixed
with multiplication or division.
	
Generally, only the first 6 characters of identifiers are significant
and numeric constants are evaluated in octal.

Other assembly language features are illustrated below:

	/ Comments may stand on lines by themselves
				/ Blank lines are allowed

		*200		/ Set the assembly origin to 200 (octal)

	NL0002=	CLA CLL CML RTL	/ Define new opcode NL0002.

		NL0002		/ Use new opcode (load 0002 in AC)
		JMP	.-1	/ Jump to the previous instruction

	X1=	10		/ Define X1 (an auto-index register address)

		TAD I	X1	/ Use autoindex register 1

		IAC; RAL	/ Multiple instructions on one line

		$		/ End of assembly

The assembly file ends with a line containing a $ (dollar sign) not in
a comment field.

The $, * and =  syntax used by most PDP-8 assemblers replace functions
performed by pseudo-operations on many other assemblers.  In addition,
PAL8, the most widely used PDP-8 assembler supports the following
pseudo-operations:

		DECIMAL		/ Interpret numeric constants in base 10
		OCTAL		/ Interpret numeric constants in base 8
		EJECT		/ Force a page eject in the listing
		XLIST		/ toggle listing
		PAGE 	 	/ Advance location counter to next page
		FIELD	N	/ Assemble into extended memory field N
		TEXT	STRING	/ Pack STRING into consecutive 6 bit bytes
		ZBLOCK	N	/ Allocate N words, initialized to zero
		IFDEF	S <C>	/ Assemble C if symbol S is defined
		IFNDEF	S <C>	/ Assemble C if symbol S is not defined
		IFZERO	E <C>	/ Assemble C if expression E is zero
		IFNZRO	E <C>	/ Assemble C if expression E is not zero

Conditonally assembled code must be enclosed in angle brackets.  The
enclosed code may extend over multiple lines.

------------------------------

Subject: What character sets does the PDP-8 support?

With its 12 bit word, the PDP-8 is somewhat awkward in its support for
modern 7 and 8 bit character sets.  Nonetheless, from the beginning,
PDP-8 software has generally assumed that text I/O would be in 7 bit
ASCII.  Most early PDP-8 systems used teletypes as console terminals;
as sold by DEC, these were configured for mark parity, so most older
software assumes 7 bit ASCII, upper case only, with the 8th bit set to
1.  On output, lines are generally terminated with both CR and LF; on
input, CR is typically (but not always) the line terminator and LF is
typically ignored.  In addition, the tab character (HT) is generally
interpreted in terms of a tab-stop every 8 spaces.

Most of the better engineered PDP-8 software tends to fold upper and
lower case on input, and it ignores the setting of the 8th bit.  Older
PDP-8 software will generally fail when presented with lower case
textual input (this includes essentially all OS/8 products prior to
OS/278 V1).

Internally, PDP-8 programmers are free to use other character sets, but
the TEXT pseudo-operation strongly encourages the 6 bit character set
called "stripped ASCII".  To map from upper-case-only ASCII to stripped
ASCII, each 8 bit character is anded with octal 77 and then packed 2
characters per word, left to right.  Many programs use a semi-standard
scheme for packing mixed upper and lower case into 6 bit TEXT form;
this uses ^ to flip from upper to lower case or lower to upper case,
% to encode CR-LF pairs, and @ (octal 00) to mark end of string.  Note
that this scheme makes no provision for encoding the %, ^ and @
characters, nor does it allow control characters other than the CR-LF
pair.  The P?S/8 operating system supports text files in this form.

Files under the widely used OS/8 system consist of sequences of 256 word
blocks.  When used for text, each block holds 384 bytes, packed 3 bytes
per pair of words as follows:

		aaaaaaaa		ccccaaaaaaaa
		bbbbbbbb		CCCCbbbbbbbb
		ccccCCCC

Control Z is used as an end of file marker.  Because most of the PDP-8
system software was originally developed for paper tape, binary object
code is typically stored in paper-tape image form using the above packing
scheme.

------------------------------

Subject: What different PDP-8 models were made?

The total sales figure for the PDP-8 family is estimated at over 300,000
machines.  Over 7000 of these were sold prior to 1970.  During the PDP-8
production run, a number of models were made, as listed in the following
table.  Of these, the PDP-8/E is generally considered to be the
definitive machine.  If the PDP-8 is considered to be the Model T of the
computer industry, perhaps the PDP-8/E should be considered to be the
industry's Model A.

    MODEL	DATES	SALES   COST	TECHNOLOGY	REMARKS

    PDP-5	63-67	 116		Transistor
    PDP-8	65-69 	1450	$18,500	Transistor
    LINC-8	66-69	 142	$38,500	Transistor
    PDP-8/S	66-70	1024	$10,000	Transistor	Very slow
    PDP-8/I	68-71 	3698	$12,800	TTL
    PDP-8/L	68-71 	3902	 $8,500	TTL		Scaled down 8/I
    PDP-12	69-73?	3500?	$27,900	TTL		Followup to LINC-8
    PDP-8/E	70-78	>10K?	 $7,390	TTL MSI	Omnibus
    PDP-8/F	72-78?	>10K?	<$7K	TTL MSI Omnibus Based on 8/E CPU
    PDP-8/M	72-78?	>10K?	<$7K	TTL MSI Omnibus OEM version of 8/F
    PDP-8/A	75-84?	>10K?	 $1,317	TTL LSI Omnibus New CPU or 8/E CPU
    VT78	78-80		<$10K	Intersil IM6100 Workstation
    DECmate I	80-84			Harris 6120	Workstation
    DECmate II	82-86		 $1,435	Harris 6120	Workstation
    DECmate III	84-90		 $2,695	Harris 6120	Workstation
    DECmate III+85-90			Harris 6120	Workstation

Additional information is available in part two of this FAQ, where all
known models of the PDP-8, along with variants, alternate marketing
names, and other peculiarities are given.

The last years of the PDP-8 family were dominated by the PDP-8 compatable
microprocessor based VT78 and DECmate workstations.  DEC also used the
Intersil IM6100 microprocessors in many peripheral controllers for the
PDP-11 and PDP-15.  While all of the earlier PDP-8 systems were open
architecture systems, the DECmates had closed architectures with an
integrated console terminals and limited peripheral options.

The following PDP-8 compatible or semi-compatible machines were made and
sold by others; very little is known about many of these:

	MODEL		DATE	MAKER, NOTES

	MP-12		6?	Fabritek (a surviving example runs FOCAL).
	TPA		68?	Hungarian, a PDP-8/L clone, ran FOKAL
	Electrotechnica-100I ?	Russian, a PDP-8/I? clone.
	Saratov-2	?	Russian, a slow clone, perhaps PDP-8/S
	Voronezh	?	Russian, another PDP-8/? clone
	SPEAR u-LINC	?	SPEAR, Inc, Waltham Mass (a LINC clone!)
	DCC-112		70-71	Digital Computer Controls
	DCC-112H	71	Digital Computer Controls
	6100 Sampler	7?	Intersil, their IM6100 promotional kit
	Intercept I	7?	Intersil, based on IM6100
	Intercept Jr	7?	Intersil, based on IM6100
	PCM-12		7?	Pacific CyberMetrix, based on Intercept bus
	PCM-12A		7?	Pacific CyberMetrix, fixed to clock at 4MHz
	SBC-8		84-88	CESI, Based on IM6120, SCSI bus
	
------------------------------

Subject: What about the LINC/8 and PDP-12?

Wesley Clark, then at Lincoln Labs, developed the LINC, or Laboratory
INstrumentation Computer, as a personal laboratory computer in the
early 1960's.  He developed it in response to the needs of Mary Brazier,
a neurophysiologist at MIT who needed better laboratory tools.  Over 24
LINC systems were built by customers before late 1964 when DEC began
selling a commercial version (see Computers and Automation, Nov. 1964,
page 43).  By the time DEC introduced the LINC-8, 43 LINC systems had
been installed (see Computers and Automation, Mar. 1966, page 34).

When Lincoln Labs decided that the LINC did not fit their mission, a
group at the the National Institute of Health funded an experiment to
see if the LINC would be a productive tool in the life sciences.  As a
result of this project, 12 LINCs were built and debugged, each by its
eventual user.

The LINC was the first 12 bit minicomputer built using DEC hardware.
Like the PDP-5 and other early DEC computers, it was built with system
modules, DEC's first family of logic modules.  Along with the CDC 160,
it paved the way for the PDP-5 and PDP-8.

When compared with the PDP-8, the LINC instruction set was not as well
suited for general purpose computation, but the common peripherals
needed for lab work such as analog-to-digital and digital-to-analog
converters were all bundled into the LINC system.  Users judged it to
be a superb laboratory instrument.

One of the major innovations introduced with the LINC was the LINCtape.
These tapes could be carelessly pocketed or dropped on the floor
without fear of data loss, and they allowed random access to data
blocks.  DEC improved on this idea slightly to make their DECtape
format, and DECtape was widely used with all DEC computers made in the
late 1960's and early 1970's.

The motives behind the development of LINCtape were the same motivives
that led IBM to develop the floppy disk almost a decade later, and in
fact, DECtape survived as a widely used medium until DEC introduced the
RX01 8 inch floppy disk drive around 1975, and even after this, DECtape
was only slowly phased out.

Within a year of the introduction of the PDP-8, DEC released the LINC-8,
a machine that combined a PDP-8 with a LINC in one package.  The
success of the LINC-8 led DEC to re-engineer the machine using TTL
logic in the late 1960's; the new version was originally to be called
the LINC-8/I, but it was sold as the PDP-12.  Both the LINC-8 and the
PDP-12 had impressive consoles, with separate sets of lights and
switches for the LINC and PDP-8 halves.

The success of the LINC-8 also led to the development of a clone, the
SPEAR micro-LINC.  This machine used Motorola MECL integrated circuits
and was available for delivery in (June 1965? this date must be wrong!).

The LINC-8 and PDP-12 could run essentially any PDP-8 or LINC program,
but because they had instructions for switching between modes, a body
of software was developed that required both modes.

One feature of LINC and LINC-8 software is the common use of the graphic
display for input-output.  These machines were some of the first to
include such a display as a standard component, and many programs used
the knobs on the analog to digital converter to move a cursor on the
display in the way we now use a mouse.

LAP, the Linc Assembly Program, was the dominant assembler used on the
LINC.  WISAL (WISconson Assembly Language) or LAP6-W was the version of
this assembler that survived to run on the PDP-12.  Curiously, this
includes a PDP-8 assembler written in LINC code.

LAP6-DIAL (Display Interactive Assembly Language) evolved from this on
the PDP-12 to became the dominant operating system for the PDP-12.  The
8K version of this is DIAL MS (Mass Storage), even if it has only two
LINCtape drives.  These were eventually displaced by the OS/8 variant
known as OS/12.

------------------------------

Subject: Where can I get a PDP-8 today?

The CESI machine may still be on the market, for a high price, but
generally, you can't buy a new PDP-8 anymore.  There are quite a few
PDP-8 machines to be found in odd places on the used equipment market.
They were widely incorporated into products such as computer controlled
machine tools, X-ray diffraction machines, and other industrial and lab
equipment.  Many of them were sold under the EduSystem marketing
program to public schools and universities, and others were used to
control laboratory instrumentation.  After about 1976, Reuters bought
as many as 10,000 OMNIBUS based machines per year, with perhaps 2000 per
year going to other customers.

If you can't get real hardware, you can get emulators.  Over the years,
many PDP-8 emulators have been written; the best of these are
indistinguishable from the real machine from a software prespective,
and on a modern high-speed RISC platform, these frequently outperform
the hardware they are emulating.

Finally, you can always build your own.  The textbook "The Art of
Digital Design," second edition, by Franklin Prosser and David Winkel
(Prentice-Hall, 1987, ISBN 0-13-046780-4) uses the design of a PDP-8 as
a running example.  Many students who have used this book were required
to build working PDP-8 systems as lab projects.

------------------------------

Subject: Where can I get PDP-8 documentation?

Part II of this FAQ cites the key documents published by DEC describing
each model of the PDP-8.  These are all out of print, and DEC was in the
habit of printing much of their documentation on newsprint with
paperback bindings, which is to say, surviving copies tend to be yellow
and brittle.  DEC distributed huge numbers of catalogs and programming
handbooks in this inexpensive paperback format, and these circulate
widely on the second-hand market.  When research laboratories and
electronics shops are being cleaned out, it is still common to find a
few dusty, yellowed copies of these books being thrown out.

Douglas Jones has made a small number of bound photocopies of DEC's
1973 introduction to programming, perhaps the definitive introduction
to the PDP-8, and the other early DEC handbooks need similar treatment
before they all crumble.

Maintenance manuals are harder to find, but more valuable.  If you need
one, you usually need to find someone willing to photocopy one of the
few surviving copies.  DEC has been friendly to collectors, granting
fairly broad letters of permission to reprint obsolete documentation,
and the network makes if fairly easy to find someone who has the
documentation you need and can get copies.

------------------------------

Subject: What operating systems were written for the PDP-8?

A punched paper-tape library of stand-alone programs was commonly used
with the smallest (diskless and tapeless) configurations from the
beginning up through the mid 1970's.  Many paper tapes from this library
survive to the present at various sites!  The minimum configuration
expected by these tapes is a CPU with 4K memory, and a teletype ASR 33
with paper tape reader and punch.

The DECtape Library System was an early DECtape oriented save and restore
system that allowed a reel of tape to hold a directory of named files
that could be loaded and run on a 4K system.  Eventually, this supported
a very limited tape-based text editor for on-line program development.
This did not use the DECtape's block addressable character; the software
was based on minimal ports of the paper-tape based software described
above.

The 4K Disk Monitor System provided slightly better facilities.  This
supported on-line program development and it worked with any device that
supported 129 word blocks (DECtape, the DF32 disk, or the RF08 disk).

MS/8 or the R-L Monitor System, was developed starting in 1966 and
submitted to DECUS in 1970.  This was a disk oriented system, faster than
the above, with tricks to make it run quickly on DECtape based systems.

POLY BASIC was a BASIC only system submitted to DECUS and later sold by
DEC as part of its EduSystem marketing program.

P?S/8 was developed starting in 1971 from an MS/8 foundation.  It runs
on minimal PDP-8 configurations, supports somewhat device independant
I/O and requires a random-access device for the file system (DECtape is
random-access!).  P?S/8 runs compatably on most PDP-8 machines including
DECmates, excepting only the PDP-8/S and PDP-5.  P?S/8 is still being
developed!

OS/8, developed in parallel with P?S/8, became the main PDP-8 programming
environment sold by DEC.  The minimum configuration required was 8K words
and a random-access device to hold the system.  For some devices, OS/8
requires 12K.  There are a large number of OS/8 versions that are not
quite portable across various subsets of the PDP-8 family.  OS/78 was
developed from OS/8 to support the DECmate I, and OS/278 was developed
for the later DECmate machines.  These have unnecessary incompatabilities
with earlier versions of OS/8 and with pre-Omnibus machines.  There are
also stories that DEC included code in either OS/8 or one of its
predecessors to make it incompatable with the DCC-112.

OS8 (no slash) may still be viable.  It requires 8K of main memory, an
extended arithmetic unit, and DECtape hardware.  Unlike most PDP-8
operating systems, it uses a directory structure on DECtape compatable
with that used on the PDP-10.

TSS/8 was developed in 1968 as a timesharing system.  It required a
minimum of 12K words of memory and a swapping device.  It was the
standard operating system on the EduSystem 50 which was sold to many
small colleges and large public school systems.  Each user gets a
virtual 4K PDP-8; many of the utilities users ran on these virtual
machines were only slightly modified versions of utilities from the
Disk Monitor System or paper-tape environments.

Other timesharing systems developed for the PDP-8 include MULTI-8, ETOS,
MULTOS, and OMNI-8; some of these required nonstandard memory management
hardware.  By the mid 1970's, some of these were true virtual machine
operating systems in the same spirit as IBM's VM-370; they typically
supported some version of OS/8 running on a 32K virtual PDP-8 assigned
to each user.  Some could support different user operating systems on
each virtual machine, others supported addressing of more than 4K for
data, but limited code to field zero of a process's virtual memory.

CAPS-8 was a cassette based operating system supporting PAL and BASIC.
There are OS/8 utilities to manipulate CAPS-8 cassettes, and the file
format on cassette is compatible with a PDP-11 based system called
CAPS-11.

RTS/8 was a real-time system developed by DEC and shipped around 1978.
This was developed from an earlier system, SRT8, dating back to around
1974.  Curiously, for a system developed so late, paper-tape and DECtape
were still supported by this system.

WPS was DEC's word processing system, developed on the 8/E and widely
used on the 1980's vintage machines with a special WPS keycaps replacing
the standard keycaps on the keyboard.  It was heavily promoted on the
VT-78, and when the DECmates came out, DEC began to suppress knowledge
that DECmates could run anything else.  WPS-11 was a curious distributed
system using a PDP-11 as a file server for a cluster of VT-78 WPS systems.

COS-310, DEC's commercial operating system for the PDP-8, supported the
DIBOL language.  COS-310 was a derivative of MS/8 and OS/8, but with a
new text file format.  The file system is almost the same as OS/8, but
dates are recorded differently, and a few applications can even run under
both COS and OS/8.  COS was the last operating system other than WPS
promoted by DEC for the DECmates.

------------------------------

Subject: What programming languages are supported on the PDP-8

The PAL family of assembly languages, particularly PAL III and PAL8 are
as close to a standard assembly language as can be found for the PDP-8.
These produce absolute object code and there are versions of PAL for
minimally configured machines, although these have sever symbol table
limitations.

MACRO-8 was DEC's first macro assembly language for the PDP-8, but it
was rarely used outside the paper-tape environment.  MACREL and SABR are
assembly languages that produce relocatable output.  SABR is the final
pass for the ALICS II FORTRAN compiler, and MACREL was developed in
(unfulfilled) anticipation of similar use.  MACREL was heavily used by
the DECmate group at DEC.

There was also RALF, the relocatable assembler supporting RTPS FORTRAN,
and FLAP, an absolute assembler derived from RALF.  Both SABR and
RALF/FALP are assemblers that handle their intended applications but
have quirky and incompatible syntax.

A subset of FORTRAN was supported on both the PDP-5 and the original
PDP-8.  Surviving documentation describes a DEC compiler from 1964 and
a compiler written by Information Control Systems from 1968.  The
latter, ALICS II FORTRAN, was originally a paper tape based compiler,
but it forms the basis of the OS/8 8K FORTRAN compiler, and was also
adapted to the Disk Monitor System.

RTPS FORTRAN required 8K and a floating point processor; it had real-time
extensions and was a full implementation of FORTRAN IV (also known as
ANSI FORTRAN 66).  OS/8 F4 is RTPS FORTRAN stripped of the requirement
for hardware floating point (if the hardware is missing, it uses
software emulation).

FOCAL, an interpretive language comparable to BASIC, was available on
all models of the family, including the PDP-5 and PDP-8/S.  Varsions of
FOCAL run under PS/8, P?S/8 and other systems.

Many versions of BASIC were also available, from DEC and other sources.
DEC BASIC was widely used on PDP-8 systems sold under the EduSystem
marketing program.  A paper-tape version was available that ran in 4K,
versions for OS/8 and TSS/8, an 8K stand-alone time-sharing version,
and others.

DIBOL was DEC's attempt at competing with COBOL in the commercial arena.
It was originally implemented under MS/8 but most versions were sold to
run under the COS operating system.

Algol was available from a fairly early date.

At least two Pascal compilers were developed for the PDP-8.  One was a
Pascal-S interpreter, written in assembler, the other was a Pascal-P
compiler with a P-code interpreter written in assembler.

At least two LISP interpreters were written for the PDP-8; one runs in
4K, the other can use up to 16K.

POLY SNOBOL was a version of SNOBOL that was somewhere between
Griswald's definitions of SNOBOL 3 and SNOBOL 4.

TECO, the text editor, is available, and is also a general purpose
language, and someone is working on a PDP-8 C.  The story of TECO on the
PDP-8 is convoluted.  Russ Ham implemented TECO under his OS8 (without
a slash) system.  This version of TECO was pirated by the Oregon Museum
of Science and Industry (OMSI), where the system was ported to PS/8.
Richard Lary and Stan Rabinowitz made it more compatible with other
versions of TECO, and the result of this work is the version distributed
by DECUS.  RT-11 TECO for the PDP-11 is a port of this code.

------------------------------

Subject: Where can I get PDP-8 software?

DECUS, the DEC User Society, is still alive and well, and their submission
form still lists PAL8 and FOCAL as languages in which they accept
submissions!  The DECUS library is available on-line by anonymous FTP:

	ftp://acfcluster.nyu.edu/DECUS

To quote the README file from the current on-line catalog, "Items from
older DECUS Library catalogs are still also available (provided their
media can still be read), but machine readable catalog information is
not available for these."  Direct questions by E-mail to
INFORMATION@DECUS.ORG.

The following anonymous FTP sites contain publically accessable archives
of PDP-8 software and other information:

	ftp://ftp.telebit.com/pub/pdp8
	ftp://ftp.update.uu.se/pub/pdp8
	ftp://nickel.ucs.indiana.edu/pub/DEC/PDP8
	ftp://sunsite.unc.edu/pub/academic/computer-science/history/pdp-8

The latter archive also maintains an archive of traffic in alt.sys.pdp8
in the directory ...pdp8/usenet and an archive of traffic in the
pdp8-lovers mailing list in .../pdp8/pdp8-lovers.

The archive at Indiana contains source code for many PDP-8 compilers and
interpreters, as well as common utilities and games.

------------------------------

Subject: Where can I get additional information?

The file WHAT-IS-A-PDP8, by Charles Lasner contains considerable
additional information; this file is available by ftp from:

	ftp://ftp.telebit.com/pub/pdp8/WHAT-IS-A-PDP8

This file gives details of every PDP-8 model including the small quirks
and incompatabilities that (to be generous) allow software to determine
which model it is running on.  These quirks also make it all too easy
for careless programmers to write almost portable software with very
obscure bugs.

The mailing list pdp8-lovers@ai.mit.edu reaches a number of PDP-8 owners
and users, not all of whom have USENET feeds.  The USENET newsgroup
alt.sys.pdp8 needs to be gatewayed to this mailing list.

Many "archival" books have included fairly complete descriptions of the
PDP-8; among them, "Computer Architecture, Readings and Examples" by
Gordon Bell and Allen Newell is among the most accurate and complete
(but difficult to read).

------------------------------

Subject: What use is a PDP-8 today?

What use is a Model T today?  Collectors of both come in the same basic
classes.  First, there are antiquarians who keep an old one in the
garage, polished and restored to new condition but hardly ever used.
Once a year, they warm it up and use it, just to prove that it still
works, but they don't make much practical use of it.

PDP-8 systems maintained by antiquarians are frequently in beautiful
shape.  Antiquarians worry about dust, chipped paint, and missing
switches, and they establish newsgroups and mailing lists to help them
locate parts and the advice needed to fix their machines.

In the second class are those who find old machines and soup them up,
replacing major parts to make a hotrod that only looks like the original
from the outside, or keeping the old mechanism and putting it to uses
that were never intended.  Some PDP-8 owners, for example, have built
PDP-8 systems with modern SCSI disk interfaces!  There is serious
interest in some quarters in constructing an omnibus board that would
support an IDE disk of the variety that was mass-produced for the
IBM PC/AT.

Last, there are the old folks who still use their old machines for their
intended purposes long after any sane economic analysis would recommend
such use.  If it ain't broke, don't fix it, and if it can be fixed,
why bother replacing it?  Both Model T Fords and the classic PDP-8
machines are simple enough that end users can maintain and repair them
indefinitely.  All you need to keep a vintage -8 running are a stock
of inexpensive silicon diodes and a stock of 2N3639B or better,
2N3640 transistors.

Unlike most modern personal computers, PDP-8 systems were routinely sold
with complete maintenance manuals; these included schematic diagrams,
explanations of not only how to use the devices, but how they are built,
and suggestions to those considering building their own peripherals.
Compared with many so-called "open systems" of today, the PDP-8 was far
better documented and far more open.

Finally, the PDP-8 is such a minimal machine that it is an excellent
introduction to how computers really work.  Over the years, many students
have built complete working PDP-8 systems from scratch as lab projects,
and the I/O environment on a PDP-8 is simple enough that it is a very
appropriate environment for learning operating system programming
techniques.

------------------------------

Subject: Who's Who?

C. Gordon Bell is generally credited with the original design of the
PDP-8.  He was also involved with recommending what became the PDP-11
when that design was competing with the design that probably became the
NOVA, and as vice president of research, he oversaw the development of
the DEC VAX family.

Alan Kotok worked with Bell in working up the original specifications
of the PDP-8.

Ben Gurley designed most of the big DEC machines, starting with the
PDP-1.  The actual design work on the -8, however, was done by Ed
deCastro, who later founded Data General to build the Nova.

Ken Olson ran DEC from the beginning.

Ed Yourdon, who later became well known as a programming methodology
guru, helped hack up the PAL III assembler for the -8 from PAL II.

Richard Merrill invented FOCAL and wrote the original (1968) and classic
FOCAL-69 interpreters for the PDP-8.

Charles Lasner developed P?S/8, and he is widely known as the grand old
man of the movement to preserve these historic machines.

Wesley Clark developed the LINC while working at Lincoln Labs; this was
the first 12 bit minicomputer built with DEC parts.

Mary Allen Wilkes Clark developed the early LAP programs for the LINC.

Douglas W. Jones wrote this FAQ, but prior to the summer of 1992, he'd
never used a PDP-8.  He has also written a report on how to photocopy
and archivally bind ailing paperback books such as DEC's handouts, a
PAL-like cross assembler in C, and a UNIX-based PDP-8 emulator.

------------------------------

End of PDP-8 Frequently Asked Questions (posted every other month)
******************************************************************


From jones@cs.uiowa.edu Fri Apr  8 12:01:25 EDT 1994
Article: 757 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!news.duke.edu!MathWorks.Com!europa.eng.gtefsd.com!howland.reston.ans.net!math.ohio-state.edu!hobbes.physics.uiowa.edu!news.uiowa.edu!news
From: jones@cs.uiowa.edu (Douglas W. Jones)
Newsgroups: alt.sys.pdp8,alt.answers,news.answers
Subject: PDP-8 Summary of Models and Options (posted every other month)
Followup-To: alt.sys.pdp8
Date: Tue, 8 Apr 94 08:08:08 GMT
Organization: Computer Science, University of Iowa, Iowa City, Iowa, USA
Lines: 1204
Approved: news-answers-request@MIT.Edu
Distribution: world
Expires: 8 June 1994 08:08:08 GMT
Message-ID: <2o3m0d$ho7@nexus.uiowa.edu>
NNTP-Posting-Host: pyrite.cs.uiowa.edu
Summary: Descriptions of all models of the DEC PDP-8 computer.
	Those posting to alt.sys.pdp8 should read this.
Keywords: FAQ DEC PDP 8
Xref: bigblue.oit.unc.edu alt.sys.pdp8:757 alt.answers:2277 news.answers:19455

Archive-name: dec-faq/pdp8-models
Last-modified: Apr 7, 1994

This version of the alt.sys.pdp8 FAQ has been modified to conform to
RFC1153 USENET digest format (with exceptions due to the fact that it
is not really a digest).  This should aid in automatic conversion of
this material to HTML and other interesting formats.

Contents:

	What is this FAQ?
	What is a PDP-5?
	What is a PDP-8?
	What is a LINC-8?
	What is a PDP-8/S?
	What is a PDP-8/I?
	What is a PDP-8/L?
	What is a PDP-12?
	What is a PDP-8/E?
	What is a PDP-8/F?
	What is a PDP-8/M?
	What is a PDP-8/A?
	What is a VT78?
	What is a DECmate I?
	What is a DECmate II?
	What is a DECmate III?
	What is a DECmate III+?

----------------------------------------------------------------------

Subject:  What is this FAQ?

Frequently Asked Questions about DEC PDP-8 models and options.

	By Douglas Jones, jones@cs.uiowa.edu
	(with help from many folks)

Sites known to carry FTPable copies of this file:

	ftp://rtfm.mit.edu/pub/usenet/alt.sys.pdp8
	ftp://sunsite.unc.edu:/pub/academic/computer-science/history/pdp-8/doc

The purpose of this document is to supplement the material in the primary
"Frequently Asked Questions about the PDP-8" file with more detailed
information about the hardware and options of the different models of the
PDP-8 sold by DEC.

Although this document is something of a history of the DEC PDP-8 family,
the primary purpose of this document is as a guide and general outline to
the PDP-8 models and options likely to be encountered by those involved
in collecting and restoring systems. 

------------------------------

Subject: What is a PDP-5?

Date of introduction:  Aug 11, 1963, unveiled at WESCON.
Date of withdrawal:    early 1967.
Price: $27,000

Technology:  Built with DEC System Modules, the original line of
	transistorized logic modules sold by DEC.  Supply voltages of
	+10 and -15 volts; the logic levels -3 (logic 1) and 0 (logic 0).
	 Logic packaged on boards that were about 4.75 inches wide with
	each card mounted in a metal frame with a 22 pin edge connector.

	Input output devices were connected to the daisy-chained I/O bus
	using military-style armored cables and connectors.  Use of
	toggle switches (as opposed to slide switches) on the front
	panel was another vestige of military-style design.

Reason for introduction:  This machine was inspired by the success of
	the CDC-160, Seymour Cray's 12 bit minicomputer, and by the
	success of the LINC, a machine that was built by DEC customers
	out of System modules.  These demonstrated that there was a
	market for a small inexpensive computer, and from the start,
	DEC's advertisements were aimed at this market.  "Now you can
	own the PDP-5 computer for what a core memory alone used to
	cost: $27,000", ran one 1964 ad.

Reason for withdrawal:  The PDP-8 outperformed the PDP-5, and did so for
	a lower price.

Compatability:  The core of the PDP-8 instruction set is present, but
	memory location zero is the program counter, and interrupts are
	handled differently.  The Group 1 OPR rotate instructions cannot
	be combined with IAC or CMA; this limits the ability of the
	PDP-5 to support code from later models.

The machine did not support 3 cycle data-break (DMA transfers using
	memory to hold buffer address and word-count information), so
	many later PDP-8 peripherals could not be used on the PDP-5.
	In addition, DMA transfers are not allowed outside the program's
	current 4K data field, severely limiting software compatability
	on systems with over 4K of memory where either interrupts or
	software initiated changes to the data field during a transfer
	would cause chaos.

Standard configuration:  CPU with 1K or 4K of memory (2K and 3K versions
	were not available).

Peripherals:
	An extended arithmetic element (EAE) was available; this was an
	I/O device, using IOT instructions to evoke EAE operations.  As
	a result, it was not compatable with the later PDP-8 EAEs.  In
	addition, machines with the EAE option had a different front
	panel from those without.

	The type 552 DECtape control and type 555 DECtape transports
	were originally developed for the PDP-5.

	After the PDP-8 was introduced, DEC offered a bus converter that
	allowed the PDP-5 to support standard PDP-8 negibus ueripherals,
	so long as they avoided using 3-cycle data break transfers.  The
	standard 804 PDP-8 expander box was frequently sold as an
	upgrade to PDP-5 systems.

------------------------------

Subject: What is a PDP-8?

Date of introduction:  1965 (Unveiled March 22, in New York)
Date of withdrawal:    1968.
Also known as:
	Classic PDP-8 (to point out lack of a model suffix)
	Straight-8 (Again, points out the lack of a model suffix)
	PCP-88, an OEM label, used Foxboro Corporation.
Price: $18500

Technology:  Mostly DEC R-series logic modules; these were originally
	discrete component transistor logic, but around the time the
	PDP-8 was introduced, DEC introduced the Flip Chip, a hybrid
	diode/resistor "integrated circuit" on a ceramic substrate.
	These could directly replace discrete components on the PC
	boards, and DEC began to refer to their R-series modules as
	flip-chip modules and they even advertised the PDP-8 as an
	integrated circuit computer.  A typical flip-chip module, the
	R111, had three 2-input nand gates and cost $14, with no price
	change from 1965 to 1970.

	S-series logic modules were also used; these are essentially
	the same as their R-series cousins, but with different pull-up
	resistors for higher speed at lower fanout.  Many R and S
	series modules have trimmers that must be tuned to the context,
	making replacement of such modules more complex than a simple
	board swap.

	As with the system modules used in the PDP-5, the supply
	voltages were +10 and -15 volts and the logic levels were -3
	(logic 1) and 0 (logic 0).  Logic was packaged on boards that
	were 2.5 inches wide by 5 inches high.  The card edge connector
	had 18 contacts on 1/8 inch centers.  Some double width cards
	were used; these had two card edge connectors and were 5 1/8
	inches wide.  Machine wrapped wire-wrap technology was used on
	the backplane using 24-gauge wire.

	The "negibus" or negative logic I/O bus used -3 and 0 volt logic
	levels in 92 ohm coaxial cable, with 9 coaxial cables bundled
	per connector card and 6 bundles making up the basic bus.  4
	(originally 5) more bundles were required to support data-break
	(DMA) transfers.  Bus termination was generally kluged in with
	100 ohm resistors clipped or wrapped into the backplane,
	although a bus terminator card was occasionally used.  Some time
	after the first year of production, flat ribbon cable made of
	multiple coaxial cables was used, and later still, flat mylar
	stripline cable was used (but never recommended because it
	lacked necessary shielding).

	Core memory was used, with a 1.5 microsecond cycle time, giving
	the machine an add time of 3 microseconds.  4K of core occupied
	an aluminum box 6 inches on a side and needed numerous auxiliary
	flip-chips for support.  It is worth noting that the PDP-8 was
	about as fast as was practical with the logic technology used;
	only by using tricks like memory interleaving or pipelining
	could the machine have been made much faster.

Reason for introduction:  This machine was inspired by the success of
	the PDP-5 and by the realization that, with their new Flip-Chip
	technology, DEC could make a table-top computer that could be
	powered by a single standard wall outlet; of course, adding any
	peripherals quickly increased the power requirement!

Reason for withdrawal:  The PDP-8/I was less expensive, and after
	initial production difficulties, it equalled the performance of
	the PDP-8.

Compatability:  The core of the PDP-8 instruction set is present, but
	the Group 1 OPR instruction IAC cannot be combined with any of
	the rotate instructions.  If RAR and RAL or RTR and RTL are
	combined, the results are unpredictable (simultaneous set and
	reset of bits of AC results in metastable behavior).  The IOT 0
	instruction was used for the internal type 189 ADC, and not for
	the later CAF (clear all flags) instruction.  As a result, if
	the ADC option was not present, IOT 6004 (or microcoded
	variants) would hang the machine.

	If the extended arithmetic element is present, the SWP (exchange
	AC and MQ) instruction does not work.  This works on later
	models when the EAE is present, although it was only documented
	with the introduction of the PDP-8/E.  Finally, the EAE lacks
	the SCL (shift count load) instruction that is present on later
	models.

	On machines with 8K or more, an attempt to change the data field
	to a non-existant field caused a bizarre double-indirect and
	skip instruction execution that must be accounted for in memory
	diagnostics.

	Standard configuration:  The PDP-8 was sold as a CPU with 4K of
	memory, a 110 baud current loop teletype interface and an ASR 33
	Teletype.  In addition, the standard in-cabinet logic includes
	support for the full negibus interface, including data-break
	(DMA) transfers.

	Both a rack-mount model with rosewood trim and an elegant
	plexiglass enclosed table-top configuration were standard.  Under
	the skin, basic machine occupied a volume 33 inches high by 19
	inches wide by 22 inches deep.  The two halves of the backplane
	were mounted vertically, like the covers of a book, with the
	spine in back and circuit modules inserted from the two sides.
	Sliding the CPU out of the relay rack or removing the plexiglass
	covers allows the backplane to swung open to access the wires.

Expandability:  In-cabinet options include the type 182 extended
	arithmetic element (EAE), the type 183 memory extension control
	subsystem, and the type 189 low performance analog to digital
	converter (ADC).  Prewired backplane slots were reserved for
	all of these.

	Expansion beyond 4K of memory requires rack space for the
	rack-mounted type 184 memory module; each such module adds one
	4K field of memory, up to a maximum of 32K.  The rack-mount CPU
	occupied a large part of one rack, allowing room for a single
	type 184 memory expansion module below the CPU; generally, a
	second rack was needed for added peripherals or memory.

	At the end of the production run, some PDP-8 systems were sold
	with PDP-8/I memory, allowing room for an additional 4K without
	need for an expansion chassis.  These nonstandard machines were
	very difficult to maintain!

Peripherals:  At the time of introduction, the following negibus
	peripherals were offered.

	-- Type 750C high speed paper tape reader and control.
	-- Type 75E high speed paper tape punch and control.
	-- Type 138E analog to digital converter and multiplexor.
	-- Type 34D oscilloscope display (dual digital to analog).
	-- Type 350B incremental (CalComp) plotter control.
	-- Type 451 card reader and control.
	-- Type 450 card punch control for IBM Type 523 punch.
	-- Type 64 (later 645) Mohawk line printer and control.
	-- Type RM08 serial magnetic drum system (up to 256K words).
	-- Type 552 DECtape control (for type 555 DECtape drives).
	-- Type 57A magnetic tape control (IBM type 729 drive).
	-- Type 580 magnetic tape system.

	By 1967, the following peripherals had been added to the line:

	-- Type TC01 DECtape control for up to 8 TU55 transports.
	-- Type AF01 analog to digital converter and multiplexor.
	-- Type AA01A 3 channel digital to analog (scope display).
	-- Type AX08 parallel digital input port.
	-- Type 338 Programmed Buffered Display (vector graphics).

	By 1968, the following new peripheral had been added:

	-- Type DF32 fixed head disk system (up to 256K words).
	-- Type BE01 OEM version of the TC01 (no blinking lights).
	-- Type BE03 dual TU55 drive for the TC01 or BE01.

	Finally, as DEC abandoned the negibus, they introduced the
	DW08B negibus to posibus converter so newer posibus
	peripherals could be used on older negibus machines.

------------------------------

Subject: What is a LINC-8?

Date of introduction:  1966 (during or before March)
Date of withdrawal:    1969 (displaced by PDP-12)
Price: $38,500

Technology:  DEC Flip Chip modules, as in the PDP-8, with a LINC CPU
	partially reimplemented in Flip Chips and partially emulated
	with PDP-8 instructions.  (The original LINC was built from
	the same System Modules used in the PDP-5.)

Compatability:  Identical to the PDP-8.

Standard configuration:  The combined PDP-8/LINC CPU, plus 4K of memory
	was central to the system.  The set of peripherals bundled with
	the machine was impressive:

	-- An ASR 33 Teletype modified for the LINC character set.
	-- Two LINCtape drives.
	-- 8 analog to digital converter channels with knob inputs.
	-- Another 8 ADC channels with jack inputs.
	-- 6 programmable relay outputs, good up to 60 Hz.
	-- 1 Tektronix 560 oscilliscope, somewhat modified.

	The X and Y axis control for the scope came from DACs attached
	to the LINC's AC and MB registers, respectively.

Expandability:

	In addition to standard PDP-8 peripherals, up to 3 additional
	pairs of LINCtape drives could be added, for a total of 8 drives.
	Each pair of drives cosmetically resembled the type BE03 dual
	DECtape transport, but single drives were not available.

	Up to 2 additional ranks of 8 ADC channels could be added.

	A second oscilliscope could be added.
	
------------------------------

Subject: What is a PDP-8/S?

Date of introduction:  1966 (Unveiled, Aug 23, WESCON, Los Angeles).
Date of withdrawal:    1970.
Price: $10,000

Technology:  DEC Flip Chip modules and core memory, as in the PDP-8.
	Unlike the PDP-8, the PDP-8/S memory was mounted on quad-height
	single-width boards that plugged into the standard flip-chip
	sockets.

Reason for introduction:  This machine was developed as a successful
	exercise in minimizing the cost of the machine.  It was the
	least expensive general purpose computer made with second
	generation (discrete transistor) technology, and it was one of
	the smallest such machines to be mass produced (a number of
	smaller machines were made for aerospace applications).  It was
	also incredibly slow, with a 36 microsecond add time, and some
	instructions taking as much as 78 microseconds.  By 1967, DEC
	took the then unusual step of offering this machine for off the
	shelf delivery, with one machine stocked in each field office
	available for retail sale.

Reason for withdrawal:  The PDP-8/L vastly outperformed the PDP-8/S, and
	and it did so at a lower price.

Compatability:  The core of the PDP-8 instruction set is present, but
	there are a sufficient number of incompatabilities that, as with
	the PDP-5, many otherwise portable "family of 8" programs will
	not run on the PDP-8/S.  Perhaps the worst incompatability is
	that the Group 1 OPR instruction CMA cannot be combined with any
	of the rotate instructions; as with the PDP-8, IAC also cannot
	be combined with rotate.

Standard configuration:  CPU with 4K of memory, plus PT08 110 baud current
	loop teletype interface and teletype.  Both a rack-mount table-top
	versions were sold (both 9" high by 19" wide by 20"? deep).  The
	rack mount could be slid out of the rack on slides for for
	maintenance.

Expandability:  The CPU supported the standard PDP-8 negibus, but I/O
	bandwidth was 1/5 that of the PDP-8.  Thus, most, but not all
	PDP-8 peripherals could be used.  A few DEC peripherals such as
	the DF32 came with special options such as interleaving to slow
	them down for compatability with the PDP-8/S.  The speed problems
	were such that there was never any way to attach DECtape to this
	machine.

------------------------------

Subject: What is a PDP-8/I?

Date of introduction:  1968 (announced before December '67)
Date of withdrawal:    1971.

Technology:  DEC M-series logic modules, called M-series flip-chips
	as the term flip-chip was applied to the module format instead
	of to DEC's hybrid integrated circuits.  M-series modules used
	TTL chips, with a +5 supply, packaged on the same format board
	as was used with the original flip-chips, but with double-sided
	card-edge connectors (36 contacts instead of 18).  Modules were
	limited to typically 4 SSI ICs each.  The M113, a typical
	M-series module, had 10 2-input nand gates and cost $23 in 1967
	(the price fell to $18 in 1970).  Wire-wrapped backplanes used
	30-gauge wire.

	The PDP-8/I, as originally sold, supported the then-standard
	PDP-8 negibus.  4K words of core were packaged in a 1 inch thick
	module made of 5 rigidly connected 5 by 5 inch two-sided printed
	circuit boards.  Connectors and support electronics occupied an
	additional 32 backplane slots.

	Nominally, the core memory (which, curiously, used a negative
	logic interface!) was supposed to run at a 1.5 microsecond cycle
	time, but many early PDP-8/I systems were delivered running at a
	slower rate because of memory quality problems.  DEC went through
	many vendors in the search for good memory!  The memory interface
	was asynchronous, allowing the CPU to delay for slow memory.  DEC
	continued to make the classic PDP-8 until the problems with
	memory speed were solved.

Reason for introduction:  This machine was developed in response to the
	introduction of DIP component packaging of TTL integrated
	circuits.  This allowed a machine of about the same performance
	as the original PDP-8 to fit in about half the volume and sell
	for a lower price.

Reason for withdrawal:  The PDP-8/E made slight performance improvements
	while undercutting the price of the PDP-8/I.

Compatability:  The core of the PDP-8 instruction set is present, and
	unlike the original PDP-8, IAC can be combined with rotate in a
	single microcoded Group 1 OPR instruction.  Combined RAR and RAL
	or RTR and RTL produce the logical and of the expected results
	from each of the combined shifts.

	If the extended arithmetic element is present, the SWP (exchange
	AC and MQ) instruction works, but this was not documented.

	On large memory configurations, memory fetches from a nonexistant
	memory field take about 30 microseconds (waiting for a bus
	timeout) and then they return either 0000 or 7777 depending on
	whether the fetch was from an even or odd field.

Standard configuration:  CPU with 4K of memory, plus 110 baud current
	loop teletype interface.  Pedestal, rack-mount and table-top
	versions were made.  The pedestal mounted version was futuristic
	looking, compatable with such office fixtures as decwriters.
	In one rack-mount version, the machine was built on a backplane
	that was bolted to the back of the rack, while the front panel
	hung from the front (unlike all other rack-mounted PDP-8 models,
	this version could not be swung out for maintenance on chassis
	slides).  Finally, a boxed version was sold that could be used
	on table-top or mounted on chassis slides.

Expandability: 4K of memory could be added internally, and additional
	memory could be added externally using a rack-mounted MM8I memory
	expansion module for each 4K or 8K addition over 8K.

	The backplane of the PDP-8/I was prewired to hold a Calcomp
	plotter interface, with the adjacent backplane slot reserved
	for the cable connection to the plotter.

	Initially, the CPU was sold with bus drivers for the PDP-8
	negibus, allowing this machine to support all older DEC
	peripherals, but later machines were sold with posibus interfaces,
	and DEC made an effort to convert earlier machines to the posibus
	in the field.

	A posibus to negibus converter, the DW08A, allowed use of all
	older PDP-8 peripherals, with small modifications.  The change
	from negibus to posibus during the period of PDP-8/I production
	leads to confusion because surviving systems may have any of
	three I/O bus configurations: Negibus, early posibus, or final
	posibus.  The early posibus used the same connectors and cables
	as the negibus, with only 9 conductors per connector, while the
	final posibus used both sides of the connector paddles, for 18
	bus lines per connector.  To add to this confusion, some negibus
	PDP-8/I systems were rewired to use 18 conductor posibus cables
	while still using negative logic!

	Eventually, an add-on box was sold that allowed PDP-8/E (OMNIBUS)
	memory to be added to a PDP-8/I.  Additionally, Fabritek sold a
	24K memory box for the 8/I.

------------------------------

Subject: What is a PDP-8/L?

Date of introduction:  1968 (announced before August '68)
Date of withdrawal:    1971.
Price: $8,500

Technology:  DEC M-series flip Chip modules, as in the PDP-8/I, with the
	same core memory as the 8/I, but the memory cycle cycle time was
	downgraded to 1.6 microseconds to avoid the speed problems of
	the -8/I.

	The positive I/O bus, or posibus, was a 100 ohm bus clamped
	between 0 and 3 volts with TTL drivers and receivers.  This was
	packaged with 18 signal lines per 2-sided interconnect cable,
	using mylar ribbon cable in most cases.  Electrically, coaxial
	cable could be used, but the slots in the CPU box were too small
	to allow convenient use of this option.

Reason for introduction:  This machine was developed as a moderately
	successful exercise using M-series logic to produce a lower cost
	but moderately fast machine.  The idea was to cut costs by
	limiting provisions for expansion.

Reason for withdrawal:  The PDP-8/E made performance improvements while
	slightly undercutting the price of the PDP-8/L.

Compatability:  The core of the PDP-8 instruction set is present, but
	all Group 3 OPR instructions are no-ops, even the Group 3 version
	of the CLA instruction.  This is because there was no provision
	made for adding an EAE to this machine.  Microcoding RAR and RAL
	together works as in the PDP-8/I.  Finally, a new front panel
	feature was added, the protect switch.  When thrown, this makes
	the last page of the last field of memory read-only (to protect
	your bootstrap code).

	The instruction to change the data field on an 8/L becomes a
	no-op when the destination data field is non-existant; on all
	other machines, attempts to address non-existant fields are
	possible.  One option for expanding the 8/L was to add a box that
	allowed 8/E memory modules to be added to the 8/L; when this
	was done, access to nonexistant data fields becomes possible and
	always returns 0000 on read.

Standard configuration:  A CPU with 4K of memory, plus 110 baud current
	loop teletype interface was standard.  Both rack-mount and
	table-top versions were sold (both 9" high by 19" wide by 21"
	deep).  The backplane was on top, with modules plugged in from
	the bottom.  The rack-mount version could be slid out for
	maintenance.

Expandability:  The CPU supported a new bus standard, the PDP-8 posibus.
	There is little space for in-box peripherals, but an expander
	box with the same volume as the CPU was available, the BA08A;
	this was prewired to hold an additional 4K of memory and to
	support in-box peripheral interfaces for such devices as the
	PDP-8/I Calcomp plotter interface.

	DEC eventually offered the BM12L, an 8K expansion box, allowing
	12K total memory on a PDP-8/L.  Curiously, this contains
	precisely the modules needed to upgrade a 4K PDP-8/I or PDP-12
	to an 8K machine, or to populate an MM8I box to add 8K of
	additional memory to an 8/I or PDP-12.

	Finally, DEC eventually offered a box allowing PDP-8/E (OMNIBUS)
	memory to be used with the PDP-8/L.  PDP-8/L configurations with
	over 8K of memory were awkward because the front panel only
	showed one bit of the extended memory address.  As a result,
	extra lights and switches for the additional bits of the memory
	address were mounted on the front of the memory expander boxes
	for the large configurations.

	A variety of posibus peripherals were introduced, most of which
	were built with the option of negibus interface logic (the -P
	and -N suffixes on these new peripherals indicated which was
	which).  Many early PDP-8/L systems were sold with DW08A bus
	level converters to run old negibus peripherals.

	Posibus peripherals introduced after the PDP-8/L (and also used
	with posibus versions of the PDP-8/I) included:

	-- The TC08P DECtape controller (for 8 TU55 or 4 TU56).
	-- The DF32D-P fixed head disk controller (a posibus DF32).
	-- The FPP-12 floating point processor.
	-- The TR02 simple magnetic tape control.
	-- The RK08 disk subsystem, 4 disk packs, 831,488 words each.

------------------------------

Subject: What is a PDP-12?

Date of introduction:  1969 (February or earlier).
Date of withdrawal:    1973.
Price: $27,900

Technology:  DEC M-series flip Chip modules, as in the PDP-8/I.

Reason for introduction:  This machine was developed as a follow-up to
	the LINC-8.  Originally it was to be called the LINC-8/I, but
	somehow it got its own number.  In effect, it was a PDP-8/I with
	added logic to allow it to execute most of the LINC instruction
	set, with trapping and software emulation used more selective
	than on the LINC-8.

Reason for withdrawal:  The LAB-8/E and the LAB-11 (a PDP-8/E and a
	PDP-11/20 with lab peripherals) eventually proved the equal of
	the PDP-12 in practice, and LINC compatability eventually proved
	to be of insufficient value to keep the machine alive in the
	marketplace.
		
Compatability:  This machine is fully compatable with the PDP-8/I, with
	additional instructions to flip from PDP-8 mode to LINC mode and
	back.  IOT 0 could enable the API, causing trouble with later
	PDP-8 code that assumes IOT 0 is "Clear all flags".  Also, the
	DECtape instruction DTLA (6766) becomes part of a stack-oriented
	extension to the instruction set, PUSHJ, on late model (or field
	updated) machines with the KF12-B backplane.

Standard configuration:  PDP-8/LINC CPU with 4K of memory, plus 110 baud
	current loop interface, plus output relay registers.  In
	addition, the standard configuration included either two TU55 or
	one TU56 drive, with a PDP-12 only controller allowing it to
	handle LINCtape.  In additoon, a 12" scope was always included,
	with a connector that can connect to a second scope.

Expandability:  An analog to digital converter and multiplexor was needed
	to fully support knob-oriented LINC software.

	Other options included:

	-- the KW12 programmable lab clock.
	-- additional TU55 or TU56 drives (up to 8 transports).
	-- the PRTC12F option to allow DECtape as well as LINCtape.
	-- the PC05 paper tape reader punch.

------------------------------

Subject: What is a PDP-8/E?

Date of introduction:  1970 (during or before August).
Date of withdrawal:    1978.
Also known as:
	Industrial-8 (with a red color scheme)
	LAB-8/E (with a green color scheme)
Price: $7,390

Technology:  Nominally made from DEC M-series flip Chip modules, but in
	a new format, quad-wide (10.5 inch wide), double-height (9 inch
	high, including card-edge connector, excluding handles).  SSI
	and MSI TTL logic were used on these boards, and the entire CPU
	fit on 3 boards.

	Interconnection between boards was through a new bus, the OMNIBUS.
	This eliminated the need for a wire-wrapped backplane, since all
	slots in the bus were wired identically.  A new line of peripheral
	interfaces was produced, most being single cards that could be
	plugged directly into the inside the main enclosure.  These
	included a set of posibus adapters allowing use of older
	peripherals on the new machine.

	Interboard connectors were needed for some multiboard options,
	including the CPU and memory subsystems.  These used standard
	36-pin backplane connectors on the opposite side of the board
	from the backplane.  Some boards, notably memory boards, had a
	total of 8 connector fingers, 4 for the omnibus and 4 for
	interboard connectors.

	The core memory cycle time was 1.2 or 1.4 microseconds,
	depending on whether a read-modify-write cycle was involved.  A
	4K core plane was packaged on a single quad-wide double-high
	board, with most of the drive electronics packed onto two
	adjacent boards.  Soon after the machine was introduced, an 8K
	core plane was released in the same format.

Reason for introduction:  The cost of the PDP-8/I and PDP-8/L was
	dominated by the cost of the interconnect wiring, and this cost
	was high as a result of the use of small circuit boards.  By
	packing a larger number of chips per board, similar function
	could be attained in a smaller volume because less interboard
	communication was required.  The PDP-8/E exploited this to achieve
	a new low in cost while attaining a new high in performance.

Reason for withdrawal:  This machine was slowly displaced by the PDP-8/A
	as the market for large PDP-8 configurations declined in the face
	of pressure from 16 bit mini and microcomputers.

Compatability:  As with the PDP-8/I and PDP-8/L, there are no limits on
	the combination of IAC and rotate instructions.  Unlike the early
	machines, basic Group 3 OPR operations for loading and storing
	the MQ register work even if there is no extended arithmetic
	element.  Finally, a new instruction was added, BSW; this swaps
	the left and right bytes in AC, and is encoded as a Group 1 OPR
	instruction using the "double the shift count bit".

	An odd quirk of this machine is that the RAL RAR combination ands
	the AC with the op-code, and the RTR RTL combination does an
	effective address computation loading the high 5 bits of AC with
	the current page and the lower bits of AC with the address field
	of the OPR instruction!

	The EAE has a new mode, mode B.  Previous EAE designs were
	single-mode.  Mode B supports a large set of 24 bit operations
	and a somewhat more rational set of shift operations than the
	standard EAE.  All prior EAE designs would hang on the microcoded
	CLA NMI (clear/normalize) instruction applied to a nonzero AC.
	This instruction is redefined to be a mode changing instruction
	on the 8/E.

Standard configuration:  A CPU with 4K of memory, plus 110 baud current
	loop teletype interface.  Both a rack-mount table-top versions
	were sold (both 9" high by 19" wide by 21" deep).  The rack mount
	version was mounted on slides for easy maintenance.  The OMNIBUS
	backplane was on the bottom, with boards inserted from the top.

	The standard OMNIBUS backplane had 20 slots, with no fixed
	assignments, but the following conventional uses:

	-- KC8E programmer's console (lights and switches)
	-- M8300 \_ KK8E CPU registers
	-- M8310 /  KK8E CPU control
	--
	--
	-- M833  - Timing board (system clock)
	-- M865  - KL8E console terminal interface.
	--
	--
	--   -- space for more peripherals
	--
	--
	-- M849  - shield to isolate memory from CPU
	-- G104  \
	-- H220   > MM8E 4K memory
	-- G227  /
	--
	--   -- space for more memory
	--
	-- M8320 - KK8E Bus terminator

	Most of the early boards with 3 digit numbers were defective
	in one way or another, and the corrected boards added a trailing
	zero.  Thus, the M833 was generally replaced with an M8330, and
	the M865 was replaced with the M8650.

Expandability:  The following are among the OMNIBUS boards that could be
	added internally:

	-- M8650 - KL8E RS232 or current loop serial interface.
	-- M8340 \_ Extended arithmetic element.
	-- M8341 /  (must be attached in two slots adjacent to CPU.
	-- M8350 - KA8E posibus interface (excluding DMA transfers).
	-- M8360 - KD8E data break interface (one per DMA device).
	-- M837  - KM8E memory extension control (needed for over 4K).
	-- M840  - PC8E high speed paper tape reader-punch interface.
	-- M842  - XY8E X/Y plotter control.
	-- M843  - CR8E card reader interface.

	There were many other internal options.  There was room in the
	basic box for another 20 slot backplane; taking into account the
	2 slots occupied by the M935 bridge between the two backplanes,
	this allowed 38 slots, and a second box could be added to
	accomodate another 38 slot backplane, bridged to the first box by
	a pair of BC08H OMNIBUS extension cables.

	Given a M837 memory extension control, additional memory could be
	added in increments of 4K by adding G104, H220, G227 triplets.
	The suggested arrangement of boards on the OMNIBUS always
	maintained the M849 shield between memory other options.  The
	one exception was that the M8350 KA8E and M8360 KD8E external
	posibus interfaces were typically placed at the end of the
	OMNIBUS right before the terminator.

	The following options were introduced later, and there were many
	options offered by third party suppliers.

	-- G111  \
	-- H212   > MM8EJ 8K memory
	-- G233  /
	-- M8357 -- RX8E interface to RX01/02 8" diskette drives.
	-- M7104 \
	-- M7105  > RK8E RK05 Disk Interface
	-- M7106 /
	-- M8321 \
	-- M8322  \ TM8E Magtape control for 9 track tape.
	-- M8323  /
	-- M8327 /

	At one point, DEC packaged a PDP-8/E in a desk with no front panel
	controls other than power and bootstrap switch, along with an RX01
	accessable from the front and a VT50 on top.  This was sold as
	the Class-ic system, with an intended market in the classroom
	(hence the name); it was the forerunner, in terms of packaging,
	of many later DEC office products.

------------------------------

Subject: What is a PDP-8/F?

Date of introduction:  1972.
Date of withdrawal:    1978.

Technology:  an OMNIBUS machine, as with the PDP-8/E.  First use
	of a switching power supply in the PDP-8 family.

Reason for introduction:  The PDP-8/E had a large enough box and a large
	enough power supply to accomodate a large configuration.  By
	shortening the box and putting in a small switching power supply,
	a lower cost OMNIBUS machine was possible.

Reason for withdrawal:  The PDP-8/A 800 displaced this machine, providing
	similar expansion capability at a lower cost.

Compatability:  The PDP-8/F used the PDP-8/E CPU and peripherals.

Standard configuration:  Identical to the PDP-8/E, except that the KC8E
	front panel was replaced with a KC8M front panel that had LEDs
	instead of incandescent lights; this front panel could also be
	installed on PDP-8/E systems, but the PDP-8/E front panel could
	not be used on a PDP-8/F because of the lack of a +8 supply for
	the lights.  The original PDP-8/F box had a defective power
	supply, but a revised (slightly larger) box corrected this
	problem.

Expandability:  This machine could be expanded using all PDP-8/E OMNIBUS
	peripherals, including the external expansion chassis.  The
	relatively small internal power supply and the lack of room for
	a 20 slot bus expander inside the first box were the only
	limitations.  There were minor compatability problems with some
	options, for example, the power-fail auto-restart card, as
	originally sold, was incompatable with the PDP-8/F power supply.

------------------------------

Subject: What is a PDP-8/M?

Date of introduction:  1972.
Date of withdrawal:    1978.

Technology:  This machine was a PDP-8/F (with a PDP-8/E CPU)

Reason for introduction:  DEC knew that OEM customers were an important
	market, so they packaged the PDP-8/F for this market, with no
	hardware changes behind the front panel.

Reason for withdrawal:  Same as the PDP-8/F

Compatability:  The PDP-8/M used the PDP-8/E CPU and peripherals.

Standard configuration:  Identical to the PDP-8/F, except that the KC8M
	front panel was replaced with a minimal function panel and the
	color scheme was different.  Because of this, one of the following
	options were required:

	-- M848  -- KP8E Power fail and auto-restart.
	-- M847  -- MI8E Hardware Bootstrap Loader.

	Expandability:  All options applying to the PDP-8/F applied.  In
	addition, the KC8M front panel (standard with the PDP-8/F) was
	available as an option.

------------------------------

Subject: What is a PDP-8/A?

Date of introduction:  1975
Date of withdrawal:    1984

Technology:  This machine used the OMNIBUS with a new single-board CPU,
	made possible by the use of TTL MSI and LSI components on an
	extra-wide board (formally, hex wide, double high) with 6 connector
	fingers instead of the usual 4.

Reason for introduction:  Using TTL MSI and LSI components, DEC was able
	to reduce the PDP-8 CPU to a single hex wide double high card.
	Similarly, they were able to make an 4K core memory card, and
	later, an 8K board in this format, and they were able to introduce
	a static RAM card using semiconductor memory.  The net effect was
	to reduce the minimum system to 3 boards.

	In addition, the market for the PDP-8 was dominated by small
	systems, with fewer and fewer customers needing large-scale
	expandability.  Thus, the 20 slot backplane of the early Omnibus
	machines was too big; with the new single board CPU and memory,
	a 12 slot backplane was enough.

Reason for withdrawal:  The market for the PDP-8 family was shrinking in
	the face of pressure from larger minicomputers and the new
	monolithic microcomputers.  After 1975, many PDP-8 sales were to
	captive customers who had sufficient software investments that
	they could not afford to move.  Only the word-processing and
	small business markets remained strong for first-time PDP-8
	sales, and in these, the specialized DEC VT-78 and DECmate
	machines were more cost effective than the open architecture
	OMNIBUS machines.
		
Compatability:  The new PDP-8/A CPU was largely compatable with the
	PDP-8/E CPU, except that the combination of RTR and RTL (Group 1
	OPR instructions) loaded the next address.  The power-fail
	auto-restart option included the standard skip on power low
	instruction, but also a new skip on battery empty instruction to
	test the battery used for back-up power on the new solid state
	memory.

Standard configuration:  The PDP-8/A was sold with a new short OMNIBUS
	backplane, mounted on its side above a power supply and a
	battery to back up the solid state memory.  The minimum
	configuration included a limited function control panel and the
	following components on the bus:

	-- M8315 -- KK8A CPU board
	-- M???? -- MS8A 1K to 4K solid state memory.
	-- M8316 -- DKC8AA serial/parallel interface and clock.

	The M8316 board contained a remarkable but useful hodgepodge of
	commonly used peripherals, including the console terminal
	interface, a parallel port, the power/fail auto-restart logic,
	and a 100 Hz real time clock.

	The original configuration sold had a 10 slot backplane and a
	poor power supply.  The later base model had a 12 slot backplane,
	the 8/A 400.

Expandability:  All PDP-8/E peripherals and options could be used with
	the PDP-8/A.  The KK8A cpu was not as fast as the KK8E used in
	the PDP-8/E, but the KK8E CPU could be substituted for the KK8A
	CPU, and many PDP-8/A systems were sold with this substitution.

	A box with a 20 slot backplane, the 8/A 800, was available for
	large configurations.  A pair of PDP-8/A backplanes could be
	connected using BC08H cables, and there was a special cable,
	the BC80C, for connecting a hex wide 8A backplane to a PDP-8/E,
	-8/F or -8/M backplane.

	By late 1975, the PDP-8/A was being sold in a workstation
	configuration, with the CPU and dual 8" diskette drives in a desk
	with a video terminal (VT57?) on top.  This followed the pattern
	set by the Class-ic packaging of the PDP-8/E, but it was aimed
	at the word-processing market.

	The following additional PDP-8/A (hex) boards were offered:

	-- G649  \_ MM8AA 8K Core stack (too slow for 8/E CPU!).
	-- H219A /  MM8AA 8K Core memory control.
	-- G650  \_ MM8AB 16K Core stack (ok for 8/E CPU!).
	-- H219B /  MM8AB 16K Core memory control.
	-- M???? -- MR8F 1K ROM (overlayable with RAM).
	-- M8317 -- KM8A memory extender (with variations).
	-- M8319 -- KL8A 4 channel RS232 or current loop serial I/O.
	-- M???? -- RL8A controller for 1 to 4 RL01/RL02 disk drives.

	-- M8416 -- KT8AA Memory management unit for up to 128K.
	--          KC8AA Programmer's Console (requires M8316)
	-- M8417 -- MSC8DJ 128K DRAM MOS Memory.

	Note that memory extension to 128K was a new PDP-8/A feature that
	was necessarily incompatable with the older PDP-8 memory expansion
	options, although the conventional PDP-8 memory expansion
	instructions still operate correctly on the first 32K.  Access to
	additional fields involved borrowing IOT instructions that were
	previously dedicated to other devices.

	The MM8A options require the use of a box with a -20V power supply.
	Also, the use of the MSC8 DRAM memory cards requires a CPU that
	supports the memory stall signal, early PDP-8/E CPUs did not.

------------------------------

Subject: What is a VT78?

Date of introduction:  1978
Date of withdrawal:    1980 (Displaced by the DECmate)
Also known as:  DECstation 78 

Technology:  Intersil 6100 microprocessor, packaged in a VT52 case.  The
	6100 processor was able to run at 4 MHz, but in the VT78, it was
	only clocked at 2.2 MHz because of the speed of the DRAM used and
	the deliberate use of graded out chips.

Reason for introduction:  Using TTL MSI and LSI components, DEC could
	pack their CPU into vacant space in a standard terminal case,
	allowing PDP-8 systems to compete with personal computers in the
	small business and office automation market.  This was a natural
	follow-on to the desk-mounted workstation configurations in which
	the PDP-8/A was already being sold.

Compatability:  The Group I OPR combinations RAL RAR and RTL RTR are
	no-ops.  Unlike all earlier PDP-8 models, autoindex locations
	10 to 17 (octal) only work in page zero mode; these operate like
	all other memory location when addressed in current page mode
	from code running on page zero.  Other than this, it is fully
	PDP-8/E compatable, even at the level of I/O instructions for
	the standard periperals; this was the last PDP-8 to offer this
	level of compatability.

	It was not possible to continue from a halt without restarting
	the machine.  In addition, none of the peripherals available on
	this machine needed DMA (data break) transfers.

Standard configuration:  The VT78 was sold with 16k words of DRAM with
	the keyboard and display of the VT52 terminal.  An RX01 dual 8"
	diskette drive was standard, packaged in the pedestal under the
	terminal.  The console (device 03/04), the printer (output only)
	port (device 66), and the serial ports (devices 30/31 and 32/33)
	are compatable with the M8650 KL8E, with the latter extended to
	allow software controlled baud rate selection.  The parallel port
	(device 47) and 100Hz clock are compatable with the comparable
	PDP-8/A options on the M8316 DKC8AA.

	The standard ROM boots the system from the RX01 after setting the
	baud rates to match that selected by the switches on the bottom
	of the VT52 case.

Expandability:  This was a closed system, with few options.  The base
	configuration was able to support two RX01 drives (later RX02),
	for a total of 4 transports.  Various boot ROM's were available,
	including a paper-tape RIM loader ROM for loading diagnostics
	from tape.  Another ROM boots the system from a PDP-11 server in
	the client/server configuration used by WPS-11.

------------------------------

Subject: What is a DECmate I?

Date of introduction:  1980
Date of withdrawal:    1984 (Phased out in favor of the DECmate II)
Also known as:  DECmate (prior to the DECmate II, no suffix was used)
		VT278

Technology:  Based on the Intersil/Harris 6120 microprocessor,
	packaged in a VT-100 box with keyboard and display.

Reason for introduction:  This machine was aimed primarily at the market
	originally opened by the VT78, using the IM6120 as a substitute
	for the older 6100 chip and optimizing for minimum cost and mass
	production efficiency.

Compatability:  A new feature was introduced in the 6120 microprocessor:
	The Group I OPR combination RAL RAR was defined as R3L, or rotate
	accumulator 3 places left, so that byte swap (BSW) is equivalent
	to R3L;R3L.  RTR RTL remained a no-op, as in the 6100.

	Also, the EAE operations not implemented in the basic CPU cause
	the CPU to hang awaiting completion of the operation by a
	coprocessor.  Unfortunately, no EAE coprocessor was ever offered.

	The printer port offered software baud-rate selection compatable
	with the VT78 baud-rate selection scheme.  The data communications
	option was completely incompatable with all previous PDP-8 serial
	ports.

	The console and printer ports are not fully compatable with the
	earlier PDP-8 serial ports.  Specifically, on earlier serial
	interfaces, it was possible to test flags without resetting them,
	but on the DECmate machines, testing the keyboard input flag
	always resets the flag as a side effect.  In addition, on the
	console port, every successful test of the flag must be followed
	by reading a character or the flag will never be set again.

	It was not possible to continue from a halt without restarting
	the machine.

	The large amount of device emulation performed by the CPU in
	supporting screen updates severely limits the ability of the
	system to run in real time.

Standard configuration:  The DECmate I was sold with 32k words of memory,
	with a small additional control memory added to handle
	control/status and boot options.  The console terminal keyboard
	and display functions are largely supported by so-called
	slushware routines in oontrol memory (a less expensive alternative
	to dedicating hardware for this, as was done in the VT78).

	The DECmate I came with an integral printer port, compatable with
	the VT78 (device 32/33), and it had an RX02 dual 8 inch diskette
	drive, mounted in the short cabinet under the terminal/CPU box.
	A 100Hz clock was included, as in the VT78 and PDP-8/A.

Expandability:  This was a closed system, with limited options.
	Specifically, a second RX02 could be connected (or an RX01,
	because that had a compatable connector), the DP278A and DP278B
	communications boards (really the same board, but the DP278B had
	2 extra chips), and the RL-278 disk controller, able to accomodate
	from 1 to 4 RL02 rack mount disk drives.

	When the DP278A option is added, additional control memory is
	included containing a ROM-based terminal emulator allowing
	diskless operation.  The emulator is an extended VT100 subset that
	is essentially compatable in 80 column mode.  The DP278A option
	could support both asynchronous and synchronous protocols, and
	the DP278B could handle SDLC and other nasty bit-stuffing
	protocols.

	Various pedestal and desk configurations were sold for housing
	the RX01 and RX02 drives, most being teacart style designs, but
	there was also a pedestal version that was essentially a
	repackaging of the RX02 with either 2 or 4 new 8 inch disk
	transports (physically incompatable with tearlier DEC transports).

------------------------------

Subject: What is a DECmate II?

Date of introduction:  1982
Date of withdrawal:    1986 
Price: $1,435

Technology:  Based on the 6120 microprocessor, this shared the same
	packaging as DEC's other competitors in the PC market, the
	Rainbow (80x86 based) and the PRO-325 (PDP-11 based).

Reason for introduction:  This machine was introduced in order to allow
	more flexibility than the DECmate I and to allow more sharing of
	parts with the VT220 and DEC's other personal computers.

Compatability:  Same as the DECmate I, except it could continue from a
	halt.  There was better hardware for device emulation support,
	allowing for somewhat better real-time performance, and the data
	communications port was an incompatable improvement on the
	incompatable DECmate I communications port.  The improved data
	communications port make it essentially as powerful as the
	DP-278B on the DECmate I, with a more efficient but bizarre
	software interface.

Standard Configuration:  The DECmate II was sold with 32K of program
	memory, plus a second full bank for dedicated control panel
	function emulation, an integral RX50 dual 5 1/4 inch diskette
	drive with an 8051 controller chip, a printer port, a 100Hz
	real-time clock, single data communications port, and interfaces
	to the monitor and keyboard.  The diskette drive can read
	single-sided 48 track-per-inch diskettes, so it might be possible
	to read (but not write) IBM PC diskettes on it.

Expandability:  This was the most open of the DECmate systems, with a
	number of disk options:  An additional pair of RX50 drives could
	be added, and with the RX78 board, it could support a pair of
	dual 8 inch drives, either RX01 or RX02.

	As an alternative to the RX78, there was a controller for an
	MFM hard drive.  The interface to the RX78 board wasn't fully
	compatable with earlier interfaces to RX01 and RX02, and there
	was no way to have both an RX78 and an MFM drive.  The MFM drive
	could be up to 64 MB, with 16 sectors per track, 512 bytes each
	and at most 8 heads and 1024 (or possibly 4096) cylinders.  A
	power supply upgrade was needed to support the MFM drive.  DEC
	sold this machine with 5, 10 and 20 meg hard drives, Seagate
	ST-506, 412, and 225 respectively.

	A graphics board supporting a color monitor could be added in
	addition to the monochrome console display.

	A coprocessor board could be added, with communication to and
	from the coprocessor through device 14.  DEC sold three boards,
	an APU board (Z80 and 64K), and two XPU boards (Z80, 8086 and
	either 256K or 512K).  If these added processors are used, the
	6120 processor is usually used as an I/O server for whatever
	ran on the coprocessor.  The XPU boards used a Z80 for I/O
	support, so 8086 I/O was very indirect, particularly if it
	involved I/O to a PDP-8 device that was emulated from control
	memory.  Despite this, the DECmate version of MS/DOS is generally
	faster than MS/DOS on more recent 80286 and 80386 based IBM PCs
	because of effective use of the coprocessors (but they couldn't
	run MS/DOS code that bypasses MS/DOS for I/O).

------------------------------

Subject: What is a DECmate III?

Date of introduction:  1984
Date of withdrawal:    1990 
Price: $2,695

Technology:  Same as the DECmate II.

Reason for introduction:  Again, DEC discovered that the market for large
	systems was dominated by other products, and that the PDP-8 based
	products were rarely expanded to their full potential.  Thus,
	there was no point in paying the price of expandability.

Compatability:  Same as the DECmate II, except that the printer port is
	fixed at 4800 baud.

Standard Configuration:  The DECmate III was sold with 32K of program
	memory, plus a second full bank for dedicated control panel
	functions, an integral RX50 dual 5 1/4 inch diskette drive with
	an 8051 controller chip, a printer port, a 100Hz real-time-clock,
	a data communications port, and interfaces for the VR-201 monitor
	and keyboard.

Expandability:  A revised version of the Z80 based coprocessor for the
	DECmate II was available, and a graphics board compatable with
	the later DECmate II graphics board could be added allowing the
	standard monochrome monitor to be replaced with a VR-241 color
	monitor.  Two monitor configurations were not supported.  An
	obscure variant of the DEC scholar modem was also supported as
	an option.

------------------------------

Subject: What is a DECmate III+?

Date of introduction:  1985
Date of withdrawal:    1990 

Technology:  Same as the DECmate II.

Reason for introduction:  This machine apparently represents the last
	gasp of the PDP-8, hunting for the remains of the ever-shrinking
	market niche that the earlier DECmates had carved out.  The
	market niche was not there, and the production runs for this
	machine were short enough that UV erasable EPROM technology was
	used where earlier DECmates had used mask programmed chips.

Compatability:  Same as the DECmate II, but the machine was unable to
	read 48 track per inch IBM formatted diskettes.  Again the
	printer port was fixed at 4800 baud.

Standard Configuration:  The DECmate III+ was sold with 32K of program
	memory, plus a second bank for dedicated control panel functions,
	an integral RX33 single 5 1/4 inch diskette drive with an 8751
	controller chip, a printer port, a data communications port and
	interfaces to the monitor and keyboard.  A hard disk controller
	compatable with the optional one on the DECmate II was included,
	supporting an integral ST-225 20 MB disk; it is likely that it
	can only handle up to 1024 cylinders, but it is otherwise
	compatable with the DECmate II.

Expandability: The same coprocessor option sold with the DECmate III was
	available, but because of the lack of a second floppy drive, this
	was rarely used (the Z80 was most likely to be used to run CP/M,
	but that system requires two drives to handle the installation
	procedure; an appropriately configured bootable image created
	on a DECmate II or III could run on a DECmate III+).

	The same graphics board as used on the DECmate III was also
	available.  The circuit traces and connectors for the Scholar
	modem are present, but this option was never sold on the
	DECmate III+.

------------------------------

End of PDP-8 Summary of Models and Options (posted every other month)
*********************************************************************


From nebosite@athena.mit.edu Mon Apr 11 17:08:02 EDT 1994
Article: 758 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!corpgate!news.utdallas.edu!wupost!decwrl!hookup!europa.eng.gtefsd.com!MathWorks.Com!news.kei.com!bloom-beacon.mit.edu!senator-bedfellow.mit.edu!athena.mit.edu!nebosite
From: nebosite@athena.mit.edu (Eric Jorgensen)
Newsgroups: alt.peace.corps,alt.personals.misc,alt.politics.elections,alt.politics.italy,alt.politics.reform,alt.polyamory,alt.prose,alt.pub.cloven-shield,alt.ql.creative,alt.rave,alt.religion.kibology,alt.revenge,alt.rock-n-roll.metal,alt.rock-n-roll.stones,alt.satanism,alt.sci.astro.fits,alt.sci.tech.indonesian,alt.security.ripem,alt.sex.fetish.fashion,alt.sex.movies,alt.sex.sounds,alt.sex.watersports,alt.shrinky.dinks,alt.smokers,alt.society.generation-x,alt.sources.amiga,alt.spleen,alt.sport.photon,alt.sports.baseball.cinci-reds,alt.sports.baseball.montreal-expos,alt.sports.baseball.stl-cardinals,alt.sports.hockey.nhl.winnipeg-jets,alt.startrek.klingon,alt.superman.dead,alt.support.diet,alt.sys.amiga.demos,alt.sys.pdp8,alt.tasteless.penis,alt.text.dwb
Subject: >>> TINY INTERNET SURVEY <<<
Date: 8 Apr 1994 22:42:42 GMT
Organization: Massachusetts Institute of Technology
Lines: 24
Distribution: world
Message-ID: <2o4ml2$e0t@senator-bedfellow.MIT.EDU>
NNTP-Posting-Host: m16-034-22.mit.edu
Keywords: internet demographics
Xref: bigblue.oit.unc.edu alt.peace.corps:3 alt.personals.misc:4288 alt.politics.elections:26976 alt.politics.italy:133 alt.politics.reform:6452 alt.polyamory:10829 alt.prose:3704 alt.pub.cloven-shield:483 alt.ql.creative:950 alt.rave:22546 alt.religion.kibology:25176 alt.revenge:1314 alt.rock-n-roll.metal:30205 alt.rock-n-roll.stones:622 alt.satanism:5974 alt.sci.tech.indonesian:472 alt.security.ripem:609 alt.sex.fetish.fashion:1025 alt.sex.movies:22633 alt.sex.sounds:524 alt.sex.watersports:312 alt.smokers:4130 alt.society.generation-x:18741 alt.sources.amiga:1818 alt.spleen:748 alt.sports.baseball.cinci-reds:454 alt.sports.baseball.montreal-expos:604 alt.sports.baseball.stl-cardinals:706 alt.sports.hockey.nhl.winnipeg-jets:390 alt.startrek.klingon:1239 alt.support.diet:8758 alt.sys.amiga.demos:5872 alt.sys.pdp8:758 alt.tasteless.penis:376 alt.text.dwb:326


Researchers at the MIT Media Lab are interested in the
demographics of internet users.  This is a tiny survey
that should take about 30 seconds to fill out and return
through email.

We would like to know-

--------------------------------------------------------

Your age:
Your country:
Your gender:
The newsgroup in which you first saw this message:

--------------------------------------------------------

Please email your reply to nebosite@athena.mit.edu
If you like, I will email the results of this survey back
to you.

Thank you for your time.

-Eric Jorgensen


From Kevin@kmurrell.demon.co.uk Mon Apr 11 17:08:20 EDT 1994
Article: 759 of alt.sys.pdp8
Newsgroups: alt.sys.pdp8
From: Kevin@kmurrell.demon.co.uk (Kevin Murrell)
Path: bigblue.oit.unc.edu!concert!inxs.concert.net!taco.cc.ncsu.edu!lll-winken.llnl.gov!sol.ctr.columbia.edu!howland.reston.ans.net!pipex!demon!kmurrell.demon.co.uk!Kevin
Subject: Emulators
Organization: Home
Reply-To: Kevin@kmurrell.demon.co.uk
X-Newsreader: Demon Internet Simple News v1.27
Lines: 11
Date: Sun, 10 Apr 1994 21:08:05 +0000
Message-ID: <766012085snz@kmurrell.demon.co.uk>
Sender: usenet@demon.co.uk

Could anyone suggest a PDP8 emulator for PC.   I see there are a few
available at the various ftp sites, but I would be gratefull for anyone to
suggest which is the 'best' for a PC.

Thanks

----------------------------------------------------------------------------
Kevin Murrell
Sutton Coldfield
Birmingham
----------------------------------------------------------------------------


From david.razler@compudata.com Wed Apr 13 08:33:56 EDT 1994
Article: 760 of alt.sys.pdp8
Newsgroups: alt.sys.pdp8
Apparently-to: ALT.SYS.PDP8
Subject: HELLLLLLP!
From: david.razler@compudata.com (David Razler)
Path: bigblue.oit.unc.edu!concert!xanth.cs.odu.edu!news.larc.nasa.gov!lerc.nasa.gov!magnus.acs.ohio-state.edu!math.ohio-state.edu!cs.utexas.edu!uunet!cmpudata!david.razler
Distribution: world
Message-ID: <12a.35.2370.0N3E0E07@compudata.com>
Date: Fri,  8 Apr 94 02:05:00 -0500
Organization: -=- Compu-Data -=- Turnersville, NJ
Lines: 35



to alt.sys.pdp8

Dear fellow three-fingered friends:
     Help! I am about to begin final restoration of a PDP-8 (slash nought) 
but I am in desperate need of the following: Doc (or better yet the real 
thing) giving full blueprints for the tabletop base, walnut side panels and 
plastic covers for the module banks (Got a welding shop willing to do the 
metal ifI can't get the Real Thing. A front panel key (yes, they were all 
the same) a schematic/physical layout for EAE boards or, perhaps, a set 
(machine came with EAE wire wrap installed, no boards, which causes one bit 
at the end of all the counters not to change) a source of assorted Teletype 
ASR-33 parts, spare modules and DEC and DECUS paper tapes. (rebuilding it as 
the classic 4K desktopper, nothing more. Have for trademanuals for DEC 18- 
and 36- bit machines, a couple of TU55s and TU56's,16 K of PDP-15 core, 
a large number of DEC SMB aluminum-frame modules,random other stuff.

  <fyi> The machinbe originally helped run Vermont's only nuclear power 
plant. ser# 8P-396 / CPU 08-1059-0100 type PDP-8-347 / EAE (without boards) 
08-1059-2100 / Teleprinter interface control 08-1059-0200 type 648 / memory 
extention controller 08-1059-1500 type 183 / core 08-1059-1000 type 184A 
(stack by Electronic Memories Inc, Hawthorne, Ca. spec. MFCS-5-13 s/n/ 30732 
wt 4367.

  Thanks to anyone who can help or at least wish me luck.
                                  dmr
                   (david.razler@compudata.com)




[david.razler@compudata.com]
---
 * WaveRdr 1.0 [NR] * UNREGISTERED EVALUATION COP


From nike@indirect.com Wed Apr 13 08:34:55 EDT 1994
Article: 761 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!inxs.concert.net!taco.cc.ncsu.edu!lll-winken.llnl.gov!decwrl!hookup!news2.sprintlink.net!news.sprintlink.net!indirect.com!nike
From: nike@indirect.com (Laurence Canter)
Newsgroups: alt.sys.pdp8
Subject: Green Card Lottery- Final One?
Date: 12 Apr 1994 08:50:27 GMT
Organization: Canter & Siegel
Lines: 34
Message-ID: <2odncj$6fk@herald.indirect.com>
NNTP-Posting-Host: id1.indirect.com

Green Card Lottery 1994 May Be The Last One!
THE DEADLINE HAS BEEN ANNOUNCED.

The Green Card Lottery is a completely legal program giving away a 
certain annual allotment of Green Cards to persons born in certain 
countries. The lottery program was scheduled to continue on a 
permanent basis.  However, recently, Senator Alan J Simpson 
introduced a bill into the U. S. Congress which could end any future 
lotteries. THE 1994 LOTTERY IS SCHEDULED TO TAKE PLACE 
SOON, BUT IT MAY BE THE VERY LAST ONE.

PERSONS BORN IN MOST COUNTRIES QUALIFY, MANY FOR 
FIRST TIME.

The only countries NOT qualifying  are: Mexico; India; P.R. China; 
Taiwan, Philippines, North Korea, Canada, United Kingdom (except 
Northern Ireland), Jamaica, Domican Republic, El Salvador and 
Vietnam. 

Lottery registration will take place soon.  55,000 Green Cards will be 
given to those who register correctly.  NO JOB IS REQUIRED.

THERE IS A STRICT JUNE DEADLINE. THE TIME TO START IS 
NOW!!

For FREE information via Email, send request to
cslaw@indirect.com


-- 
*****************************************************************
Canter & Siegel, Immigration Attorneys
3333 E Camelback Road, Ste 250, Phoenix AZ  85018  USA
cslaw@indirect.com   telephone (602)661-3911  Fax (602) 451-7617


From grant@oj.rsmas.miami.edu Wed Apr 13 23:43:28 EDT 1994
Article: 762 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!news.duke.edu!MathWorks.Com!europa.eng.gtefsd.com!howland.reston.ans.net!wupost!news.miami.edu!not-for-mail
From: grant@oj.rsmas.miami.edu (Grant Basham)
Newsgroups: alt.sys.pdp8,vmsnet.pdp-11,alt.sys.pdp11,comp.sources.wanted
Subject: Need Dec 'BRU' for BSD unix (or help)
Date: 13 Apr 1994 20:29:15 -0400
Organization: R.S.M.A.S.
Lines: 15
Message-ID: <2oi2or$9g6@oj.rsmas.miami.edu>
NNTP-Posting-Host: oj.rsmas.miami.edu
Keywords: rt-11 backup rsx unix
Xref: bigblue.oit.unc.edu alt.sys.pdp8:762 vmsnet.pdp-11:1043 comp.sources.wanted:17048

We need to get the data of a 1/4 inch cartridge tape.  The tape was written
with DEC BRU, an RSX (RT-11?) utility.  All I need to get We have a 1/4 inch
drive on a sun and I could see a few files, *.ftn, that could be half read,
but there are many files and some are quite complicated.  It would be more
than we can tackle to do it by hand.

Anyone got anything that will help in getting Fortran source code files off
the tape.  Lacking a bru2unix utility, anyone have bru on a box with a 1/4
inch drive and the ability to translate it to tar or VMS backup on something
standard (9-track, Exabyte, or DAT). Any help or ideas are greatly
appreciated.
-- 

  Grant Basham       (305)361-4026       University of Miami
  grant@oj.rsmas.miami.edu   RSMAS Computer Facility/Systems


From :KEVIN@KMURRELL.DEMON.CO.UK Thu Apr 14 19:57:18 EDT 1994
Article: 763 of alt.sys.pdp8
Newsgroups: alt.sys.pdp8
Apparently-to: KEVIN@KMURRELL.DEMON.CO.
Subject: Emulators
From:   :KEVIN@KMURRELL.DEMON.CO.UK
Path: bigblue.oit.unc.edu!concert!corpgate!news.utdallas.edu!chpc.utexas.edu!cs.utexas.edu!uunet!cmpudata!  :KEVIN
Distribution: world
Message-ID: <12a.47.2370.0N3E119B@KMURRELL.DEMON.CO.UK>
Date: Wed, 13 Apr 94 02:16:00 -0500
Organization: -=- Compu-Data -=- Turnersville, NJ
Lines: 29

  
KL>Message-ID: <766012085snz@kmurrell.demon.co.uk>
KL>Newsgroups: alt.sys.pdp8
KL>Organization: Home

KL>Could anyone suggest a PDP8 emulator for PC.   I see there are a few
KL>available at the various ftp sites, but I would be gratefull for anyone 
KL>suggest which is the 'best' for a PC.

KL>Thanks

Kevin:
  If you find a good one, please attach it to a message to me, do not have 
FTP capability yet, but I would truely like to race an emulator running on 
my '486-33 against my PDP-8 (stroke/naught - the original) Also continuing 
search for parts or blueprints of same, especially of the EAE boards (I need 
to get or make a set) and the tabletop base, walnut panels and plastic 
module covers. (also if anyone has a spare microfiche of the full specs, 
data and D-ECO-Log for the machine, I would be absolutely in your debt if I 
could borrow or buy a print-out from you)
                                             dmr
                                (david.razler@compudata.com)




[david.razler@compudata.com]
---
 * WaveRdr 1.0 [NR] * UNREGISTERED EVALUATION COP


From pjf@osiris.cs.uoguelph.ca Thu Apr 14 19:57:57 EDT 1994
Article: 764 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!gatech!howland.reston.ans.net!torn!nermal.cs.uoguelph.ca!osiris!pjf
From: pjf@osiris.cs.uoguelph.ca (Peter Jaspers-Fayer)
Newsgroups: alt.sys.pdp8,vmsnet.pdp-11,comp.sources.wanted
Subject: Re: Need Dec 'BRU' for BSD unix (or help)
Followup-To: alt.sys.pdp8,vmsnet.pdp-11,comp.sources.wanted
Date: 14 Apr 1994 12:55:23 GMT
Organization: University of Guelph
Lines: 14
Message-ID: <2ojefr$92p@nermal.cs.uoguelph.ca>
References: <2oi2or$9g6@oj.rsmas.miami.edu>
NNTP-Posting-Host: osiris.cs.uoguelph.ca
X-Newsreader: TIN [version 1.2 PL2]
Xref: bigblue.oit.unc.edu alt.sys.pdp8:764 vmsnet.pdp-11:1045 comp.sources.wanted:17056

Grant Basham (grant@oj.rsmas.miami.edu) wrote:
 >We need to get the data of a 1/4 inch cartridge tape.  The tape was written
 >with DEC BRU....

"bru" format is not DEC's, but rather a 3rd party (can't remember the 
company), licenced by many vendors. If you can find an SGI machine
anywhere, you can DD the info off the tape, FTP it there and decode it with
their "bru" (comes with every SGI). If the file is not TOO humungous, (< 5Mb)
dd it off, compress it, and I can do it for you, and send it back in
compressed TAR format.

--
 /PJ      "You can't grep dead trees"                       pjf@uoguelph.ca
                                                         (519)824-4120x6309


From dd@adobe.com Thu Apr 14 19:58:23 EDT 1994
Article: 765 of alt.sys.pdp8
Newsgroups: alt.sys.pdp8,vmsnet.pdp-11,comp.sources.wanted
Path: bigblue.oit.unc.edu!concert!decwrl!adobe!dd
From: dd@adobe.com (David DiGiacomo)
Subject: Re: Need Dec 'BRU' for BSD unix (or help)
Message-ID: <1994Apr14.191009.8594@adobe.com>
Originator: dd@gardenia
Sender: usenet@adobe.com (USENET NEWS)
Organization: Adobe Systems Incorporated
References: <2oi2or$9g6@oj.rsmas.miami.edu> <2ojefr$92p@nermal.cs.uoguelph.ca>
Date: Thu, 14 Apr 1994 19:10:09 GMT
Lines: 14
Xref: bigblue.oit.unc.edu alt.sys.pdp8:765 vmsnet.pdp-11:1048 comp.sources.wanted:17062

In article <2ojefr$92p@nermal.cs.uoguelph.ca> pjf@osiris.cs.uoguelph.ca (Peter Jaspers-Fayer) writes:
>Grant Basham (grant@oj.rsmas.miami.edu) wrote:
> >We need to get the data of a 1/4 inch cartridge tape.  The tape was written
> >with DEC BRU....
>
>"bru" format is not DEC's, but rather a 3rd party (can't remember the 
>company), licenced by many vendors. If you can find an SGI machine
>anywhere, you can DD the info off the tape, FTP it there and decode it with
>their "bru" (comes with every SGI). If the file is not TOO humungous, (< 5Mb)
>dd it off, compress it, and I can do it for you, and send it back in
>compressed TAR format.

The BRU program that is available for Unix systems has nothing to do with
the RSX BRU program, which is extremely FILES-11 specific.


From billh@comtch.iea.com Fri Apr 15 18:31:16 EDT 1994
Article: 766 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!inxs.concert.net!taco.cc.ncsu.edu!lll-winken.llnl.gov!noc.near.net!MathWorks.Com!europa.eng.gtefsd.com!howland.reston.ans.net!pipex!uunet!nwnexus!krel.iea.com!comtch!billh
From: billh@comtch.iea.com (Bill Haygood)
Newsgroups: alt.sys.pdp8
Subject: Re: Emulators
Date: 14 Apr 1994 16:58:04 GMT
Organization: CompuTech Computer Technology / Digital Video Applications
Lines: 27
Message-ID: <2ojsms$bjj@krel.iea.com>
References: <766012085snz@kmurrell.demon.co.uk>
NNTP-Posting-Host: comtch.iea.com
X-Newsreader: TIN [version 1.2 PL1]

Kevin Murrell (Kevin@kmurrell.demon.co.uk) wrote:
: Could anyone suggest a PDP8 emulator for PC.   I see there are a few
: available at the various ftp sites, but I would be gratefull for anyone to
: suggest which is the 'best' for a PC.

: Thanks

: ----------------------------------------------------------------------------
: Kevin Murrell
: Sutton Coldfield
: Birmingham
: ----------------------------------------------------------------------------

I wrote a pdp8 emulator available via ftp at (last time I looked):

    sunsite.unc.edu
    /pub/academic/computer-science/history/pdp-8/emulators/new

The files contain the ANSI C sources plus a bootable OS/8 RK05 "disk".

Just #define MS_DOS and compile to run on a PC.  Jim Van Zee wrote the 
MS-DOS specific code.  On my Amiga B2000 with 68040 running at 33MHz, 
the emulator runs at a speed of better than 500,000 pdp8 instruction 
emulations per second (approximately pdp8 hardware speed).
 _
|_)    |_|
|_)ill | |aygood


From prep@yarrow.wt.uwa.edu.au Sun Apr 17 19:27:19 EDT 1994
Article: 767 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!xanth.cs.odu.edu!news.larc.nasa.gov!darwin.sura.net!howland.reston.ans.net!cs.utexas.edu!swrinde!ihnp4.ucsd.edu!munnari.oz.au!news.uwa.edu.au!news.uwa.edu.au!prep
From: prep@yarrow.wt.uwa.edu.au (Paul Repacholi)
Newsgroups: alt.sys.pdp8
Subject: Re: Emulators
Date: 15 Apr 1994 18:48:26 GMT
Organization: The University of Western Australia
Lines: 22
Distribution: world
Message-ID: <PREP.94Apr16024826@yarrow.wt.uwa.edu.au>
References: <12a.47.2370.0N3E119B@KMURRELL.DEMON.CO.UK>
NNTP-Posting-Host: yarrow.wt.uwa.edu.au
In-reply-to: :KEVIN@KMURRELL.DEMON.CO.UK's message of Wed, 13 Apr 94 02:16:00 -0500

In article <12a.47.2370.0N3E119B@KMURRELL.DEMON.CO.UK> :KEVIN@KMURRELL.DEMON.CO.UK writes:
> my '486-33 against my PDP-8 (stroke/naught - the original) Also continuing 
> search for parts or blueprints of same, especially of the EAE boards (I need 
> to get or make a set) and the tabletop base, walnut panels and plastic 
> module covers. (also if anyone has a spare microfiche of the full specs, 
> data and D-ECO-Log for the machine, I would be absolutely in your debt if I 
> could borrow or buy a print-out from you)

What you need is " PDP-8 Maintainance MAnual ", F-87. It has everything
in it, circ diags, the lot.

It is about 4Kg...

The DEC-O-Log would be about the same, or more.

--
~Paul
                                                       +61 (09) 257-1001
prep@yarrow.wt.uwa.edu.au ( preferred )                1 Crescent Rd,
zrepachol@cc.curtin.edu.au                             Kalamunda,
                                                       West Aust    6076


From geremin@decus.org.au Tue Apr 19 06:41:54 EDT 1994
Article: 768 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!gatech!darwin.sura.net!howland.reston.ans.net!europa.eng.gtefsd.com!library.ucla.edu!ihnp4.ucsd.edu!munnari.oz.au!ariel.ucs.unimelb.EDU.AU!ucsvc.ucs.unimelb.edu.au!decus!geremin
Newsgroups: decus.nop,aus.general,alt.sys.pdp8,alt.sys.pdp11,comp.org.decus
Subject: Proposed DECUS meeting for Anzac Day in Oz.
Message-ID: <1994Apr18.231304.14871@decus.org.au>
From: geremin@decus.org.au
Date: 18 Apr 94 23:13:03 AEST
Organization: DECUS, South Pacific Chapter
Lines: 51
Xref: bigblue.oit.unc.edu alt.sys.pdp8:768 comp.org.decus:4341


   	DECUS   NOP  SIG   -   April, 94  Meeting,   Anzac Day.
        ================       =========  --------

        When :  15:00 on Monday, 25th April, 1994.

        Where:  PLC Peripherals, (distributor of QED-95 CPU upgrades).

		7 Tabletop Rd,	Terrigal,  NSW  2260.

		(Exit Sydney to the North, turn right via Gosford )
		( or Ourimbah/Wyong Road.  RSVP for more details. )


        What : Inspection of his local (non-DECnet) LAN facility, 
		plus selected PDP-11 and PC type systems.
		There is even a HP label or two (just for variety).


        Why  : Ken reckons it is time we all travelled to his site.
		He will tell us about his work with industrial sites, etc.

		Agenda topics:  NOP design of Controller Board, Mike.
				E-11 Emulator; Disk Image transfers.
				E-11 copies; distribution on RX33s.
				CMU-Tech, TCP/IP for VMS or TSX v6.3
				Strobe Data - PDP-11 in a PC box. JAG.
				Progress on Museum space (or lack of).
				NOP BBS/NEWS/e-MAIL facility.
				DECUS-94 Symposium planning.
				Free VAX-11/750 in Adelaide.
				Update on NOP/museum collections.
				Rain damage to pallet full of PDP-8 things.
				Training on NUP 2UP for Cameron.
				IN%"petition@brisnet.org.au" 
				Funny things with 'Cutler-Hammer' labels.
				May meeting - visit to Digital Express.

        RSVP :  John Geremin at  IN%"geremin@decus.com.au"
                            or phone 02-764 4855   or fax 02-764 4679.

        Wanted:   BYO food and folding chairs for the BBQ.
	                 New members welcome.  

        --------------------------------------------------------------------

Regards,   John G.		(alias 'megaJOHN')
v-v-v-v-v-v-v-v-v-v-v-v-v-v-v-v-v-v-v-v-v-v-v-v-v-v-v-v-v-v-v-v
  John Geremin,  PDP-11 Support Consultant,  MEGATRONICS, Aust.
IN%"geremin@decus.com.au"     voice: 61-2- 764 4855  (9am-9pm)
-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-^-


From jesup@cbmvax.cbm.commodore.com Tue Apr 19 06:42:35 EDT 1994
Article: 769 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!news.duke.edu!MathWorks.Com!europa.eng.gtefsd.com!library.ucla.edu!agate!darkstar.UCSC.EDU!news.hal.COM!olivea!gossip.pyramid.com!pyramid!cbmvax!jesup
From: jesup@cbmvax.cbm.commodore.com (Randell Jesup)
Newsgroups: alt.sys.pdp8,vmsnet.pdp-11,comp.sources.wanted
Subject: Re: Need Dec 'BRU' for BSD unix (or help)
Message-ID: <CoH55o.HKp@cbmvax.cbm.commodore.com>
Date: 18 Apr 94 21:32:10 GMT
References: <2oi2or$9g6@oj.rsmas.miami.edu> <2ojefr$92p@nermal.cs.uoguelph.ca>
Reply-To: jesup@cbmvax.cbm.commodore.com (Randell Jesup)
Organization: Commodore, West Chester, PA
Lines: 19
Xref: bigblue.oit.unc.edu alt.sys.pdp8:769 vmsnet.pdp-11:1055 comp.sources.wanted:17107

pjf@osiris.cs.uoguelph.ca (Peter Jaspers-Fayer) writes:
>Grant Basham (grant@oj.rsmas.miami.edu) wrote:
> >We need to get the data of a 1/4 inch cartridge tape.  The tape was written
> >with DEC BRU....
>
>"bru" format is not DEC's, but rather a 3rd party (can't remember the 
>company),

	Produced by Fred Fish.  I think his address is fnf@fishpond.com, but
check recent articles in comp.sys.amiga.announce and you should find it.
If you can't find it, let me know and I'll look it up.

-- 
GNU Emacs is a LISP operating system disguised as a word processor.
 - Doug Mohney, in comp.arch

Randell Jesup, OS Group Head, Commodore Engineering.
jesup@commodore.com (preferred) or rutgers!cbmvax!jesup
Disclaimer: Nothing I say is anything other than my personal opinion.


From bqt@Krille.Update.UU.SE Thu Apr 21 02:51:08 EDT 1994
Article: 770 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!news.duke.edu!MathWorks.Com!europa.eng.gtefsd.com!howland.reston.ans.net!EU.net!sunic!columba.udac.uu.se!Krille.Update.UU.SE!Krille.Update.UU.SE!not-for-mail
From: bqt@Krille.Update.UU.SE (Johnny Billquist)
Newsgroups: alt.sys.pdp8,vmsnet.pdp-11,alt.sys.pdp11,comp.sources.wanted
Subject: Re: Need Dec 'BRU' for BSD unix (or help)
Date: 19 Apr 1994 07:29:10 +0200
Organization: Update Computer Club
Lines: 35
Message-ID: <2ovq7k$ptr@Krille.Update.UU.SE>
References: <2oi2or$9g6@oj.rsmas.miami.edu>
NNTP-Posting-Host: krille.update.uu.se
Keywords: rt-11 backup rsx unix
Xref: bigblue.oit.unc.edu alt.sys.pdp8:770 vmsnet.pdp-11:1056 comp.sources.wanted:17111

In <2oi2or$9g6@oj.rsmas.miami.edu> grant@oj.rsmas.miami.edu (Grant Basham) writes:

>We need to get the data of a 1/4 inch cartridge tape.  The tape was written
>with DEC BRU, an RSX (RT-11?) utility.  All I need to get We have a 1/4 inch
>drive on a sun and I could see a few files, *.ftn, that could be half read,
>but there are many files and some are quite complicated.  It would be more
>than we can tackle to do it by hand.

BRU is for RSX.

>Anyone got anything that will help in getting Fortran source code files off
>the tape.  Lacking a bru2unix utility, anyone have bru on a box with a 1/4
>inch drive and the ability to translate it to tar or VMS backup on something
>standard (9-track, Exabyte, or DAT). Any help or ideas are greatly
>appreciated.

VMS systems can run BRU, if they have the proper software.
Apart from that, I'm afraid you're out of luck.

If you could get it down on a normal 1/2" tape, I could fix
it for you. I have an RSX system online, but it don't have any
1/4" drives.

If you're really desperate, maybe we can work something out anyway.
Just by doing a dd of the tape to disk, and then transferring it over
here, I do a dd back to 1/2" tape, mount the tape on the RSX system,
get the files out, and then send them to you. That should work, but
it will also take some time.

	Johnny
-- 
Johnny Billquist                  || "I'm on a bus
CS student at Uppsala University  ||  on a psychedelic trip
email: bqt@minsk.docs.uu.se       ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol


From rla@rahul.net Thu Apr 21 02:51:35 EDT 1994
Article: 771 of alt.sys.pdp8
Newsgroups: alt.sys.pdp8,alt.sys.pdp11
Path: bigblue.oit.unc.edu!concert!corpgate!bnrgate!bnr.co.uk!pipex!uunet!nwnexus!a2i!rla
From: rla@rahul.net (Bob Armstrong)
Subject: Need belt and filters for RK05 !
Message-ID: <CoGuyx.JxD@rahul.net>
Followup-To: poster
Keywords: RK05
Sender: news@rahul.net (Usenet News)
Nntp-Posting-Host: bolero
Organization: a2i network
Distribution: usa
Date: Mon, 18 Apr 1994 17:52:08 GMT
Lines: 11


  I have two RK05 drives that need new drive belts and air filters.
Can these still be found anywhere ?

  One drive is an F (fixed) and one a J (removable), but I believe
the belts and filters are the same.

Thanks,
Bob Armstrong
-- 
Bob Armstrong <rla@rahul.net>


From jones@pyrite.cs.uiowa.edu Thu Apr 21 02:52:36 EDT 1994
Article: 772 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!xanth.cs.odu.edu!news.larc.nasa.gov!lerc.nasa.gov!magnus.acs.ohio-state.edu!news.cic.net!MathWorks.Com!europa.eng.gtefsd.com!library.ucla.edu!galaxy.ucr.edu!ihnp4.ucsd.edu!swrinde!cs.utexas.edu!uunet!news.uiowa.edu!news
From: jones@pyrite.cs.uiowa.edu (Douglas W. Jones,201H MLH,3193350740,3193382879)
Newsgroups: alt.sys.pdp8
Subject: PDP-8 available in Atlanta
Date: 19 Apr 1994 21:14:18 GMT
Organization: University of Iowa, Iowa City, IA, USA
Lines: 25
Distribution: world
Message-ID: <2p1hja$cj3@nexus.uiowa.edu>
NNTP-Posting-Host: pyrite.cs.uiowa.edu

I just got this in response to a posting of mine in alt.folklore.computers,
and I thought I'd pass it along:

-- begin quote --
>From jsm@netcom.com (John Miller)

Doug, I have an old DEC (in Atlanta) that I'd like to find a new home
for, if you're ever through here in your minivan.  It's a WPS-8, or
maybe a DEC 310 -- not sure.  It's got two 8-inch drives and a VT 42?
or 48? monitor.  It works, but it boots straight into Word-11 or maybe
DecWord.  It's yours for the hauling away.

John Miller, N4VU                 Linux!                    Fayetteville
jsm@n4vu.Atl.GA.US                DoD #1942                    (Atlanta)
{emory,gatech}!n4hgf!n4vu         AMA #671301                     GA, US
-- begin quote --

Please respond to him, not to me!

				Doug Jones
				jones.cs.uiowa.edu


From jones@pyrite.cs.uiowa.edu Thu Apr 21 02:53:11 EDT 1994
Article: 773 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!news.duke.edu!news-feed-1.peachnet.edu!emory!swrinde!cs.utexas.edu!math.ohio-state.edu!hobbes.physics.uiowa.edu!news.uiowa.edu!news
From: jones@pyrite.cs.uiowa.edu (Douglas W. Jones,201H MLH,3193350740,3193382879)
Newsgroups: alt.sys.pdp8
Subject: Remex 550 High Speed Punch
Date: 20 Apr 1994 15:01:54 GMT
Organization: University of Iowa, Iowa City, IA, USA
Lines: 14
Distribution: world
Message-ID: <2p3g52$9nb@nexus.uiowa.edu>
NNTP-Posting-Host: pyrite.cs.uiowa.edu

I've just purchased a pair of Rexex model 550 high speed paper tape punches,
originally used on a PDP-8 at Collins Radion (now Rockwell Collins).
One is spool feed, the other fanfold, but they have identical punch
mechanisms and interface electronics, so I intend to treat the spoolfed
model (a bit battered) as a source of spares for the other.

Anyway, I'm trolling for documentation.  Has anyone got anything?

(Progress report -- my efforts at reverse engineering my IOmec high speed
paper tape reader interface board are almost complete.  Also, I've found
documentation for the IOmec reader I hope to interface to the board.)

				Doug Jones
				jones@cs.uiowa.edu


From david.razler@compudata.com Fri Apr 22 00:24:45 EDT 1994
Article: 774 of alt.sys.pdp8
Newsgroups: alt.sys.pdp8
Apparently-to: RLA@RAHUL.NET
Subject: Need belt and filters fo
From: david.razler@compudata.com (David Razler)
Path: bigblue.oit.unc.edu!concert!inxs.concert.net!taco.cc.ncsu.edu!hsdndev!wupost!cs.utexas.edu!uunet!cmpudata!david.razler
Distribution: world
Message-ID: <12a.59.2370.0N3E1597@compudata.com>
Date: Thu, 21 Apr 94 00:00:00 -0500
Organization: -=- Compu-Data -=- Turnersville, NJ
Lines: 25




BA>  I have two RK05 drives that need new drive belts and air filters.
BA>Can these still be found anywhere ?

BA>  One drive is an F (fixed) and one a J (removable), but I believe
BA>the belts and filters are the same.

BA>Thanks,
BA>Bob Armstrong

Try DEC Traditional Product Line, though since Ken was ousted they think a 
VAX 8600 is "traditional".
                                        dmr
                          [david.razler@compudata.com]
    
"I don't care what they may say, 12,18,36 bits are here to stay!"




[david.razler@compudata.com]
---
 * WaveRdr 1.0 [NR] * UNREGISTERED EVALUATION COP


From ard@siva.bris.ac.uk Wed Apr 27 23:15:33 EDT 1994
Article: 775 of alt.sys.pdp8
Newsgroups: alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!corpgate!news.utdallas.edu!wupost!udel!MathWorks.Com!europa.eng.gtefsd.com!howland.reston.ans.net!EU.net!uknet!gdt!bsmail!siva.bris.ac.uk!ard
From: ard@siva.bris.ac.uk (PDP11 Hacker .....)
Subject: My first PDP-8
Message-ID: <25APR199418191014@siva.bris.ac.uk>
News-Software: VAX/VMS VNEWS 1.41    
Sender: usenet@info.bris.ac.uk (Usenet news owner)
Nntp-Posting-Host: siva.bris.ac.uk
Organization: University of Bristol Physics Department
Date: Mon, 25 Apr 1994 17:19:00 GMT
Lines: 38

Greetings PDP8-lovers...
  I was walking past the local PC shop today, and could hardly believe my eyes.
Among the disk drives and half-dead MS-DOS boxes was a DECmate 2. I quickly
bought it for 10 pounds.

Now, this is my first ever PDP-8 type of machine (although I may get a PDP8e
soon), and I know little about them other than having the instruction set, and
the Intersil 6100 data sheets. So, I have lots of questions. I'll apologise in
advance if any of these are directly off the FAQ list....
Note that I have the rainbow and PRO machines, and know a little about them.
So, you don't need to tell me the really basic stuff.
OK, on with the questions

1) The machine contains an RX50 drive, PSU, and a motherboard flat in the
bottom, like a rainbow. On the motherboard is a socketed chip labeled 6120, and
some other 40 pin IC's, all labeled the same. I assume the former is the CPU
(my Intersil databook is at home, and I don't remember seeing that chip in it,
only the 6100. What's the difference?). Oh, and a 7201 (serial chip I think),
6402's (UARTs), a 1793 (floppy controller), and a 8751 (microcontroller for the
floppy controller?), along with some CRT control stuff. Is the CRT controller
standard, and if so, where can I get a data sheet

2) There are 3 (empty) 40 pin connectors on the front of the motherboard. what
are these for, and does anyone know the pinout

3) Is the monitor cable the same as a PRO/rainbow mono monitor cable. I got an
LK201 and a VR201 with it, but no cable.

4) I don't seem to have a boot disk. Anyway, the manuals seems to imply that
the machine is a dedicated word processor. Where can I get a real OS boot disk
from (free (preferably :-)), or commercial), and what OS do I run?

5) Anything else you can tell me about this toy?
-tony

Bristol University takes no responsibility for the views expressed in this
posting. They are the personal views of the user concerned.


From pan@vaxc.cc.monash.edu.au Wed Apr 27 23:15:49 EDT 1994
Article: 776 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!news.duke.edu!eff!news.kei.com!ub!dsinc!netnews.upenn.edu!msuinfo!harbinger.cc.monash.edu.au!mukluk!pan
From: pan@vaxc.cc.monash.edu.au (Pan Thongvilu)
Newsgroups: alt.sys.pdp8
Subject: Free PDP8 spares
Date: 26 Apr 1994 01:31:54 GMT
Organization: Monash University
Lines: 10
Sender: pan@kilroy.cc.monash.edu.au (Pan Thongvilu)
Distribution: world
Message-ID: <2phqua$7np@harbinger.cc.monash.edu.au>
NNTP-Posting-Host: kilroy.cc.monash.edu.au

Hi all,

I have some PDP8 spares for whoever wants them: Power supply
backplane and some logics.

The trick is I am in Melbourne, Australia.

Pan.


From supnik@human.enet.dec.com Wed Apr 27 23:16:36 EDT 1994
Article: 777 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!news.duke.edu!zombie.ncsc.mil!MathWorks.Com!europa.eng.gtefsd.com!hookup!decwrl!pa.dec.com!sousa.amt.ako.dec.com!human.enet.dec.com!supnik
From: supnik@human.enet.dec.com (Bob Supnik)
Newsgroups: alt.sys.pdp8
Subject: 1's complement arithmetic
Date: 25 APR 94 22:11:30
Organization: Digital Equipment Corporation
Lines: 29
Message-ID: <2pht8o$3k7@sousa.amt.ako.dec.com>
NNTP-Posting-Host: human.enet.dec.com
Summary: How did 1's complement arithmetic work on PDP's?
Keywords: 18b PDP's


    Here's a question from the deep dark past: how did 1's complement
    arithmetic on the 18b PDP's really work?

    According to the PDP-4 manual, when adding numbers in 1's complement,
    the carry out of the high order bit is propagated back to the low order
    bit to give the correct result:

    	-1	=	777776
    	-1	=	777776
    		     1) 777774
    		     |------>1
    	-2	=	777775

    However, if this is all that happens, then adding a number and its
    complement (x and -x) would always produce -0:

    	-1	=	777776
    	+1	=	000001
    	-0	=	777777

    Did the 18b PDP's automatically convert -0 to +0 as part of (1's
    complement) ADD?  There's a note to that effect in the ISP description
    of the PDP-1 and PDP-4 in "Computer Engineering", but I can't find any
    reference to this in the PDP-4 manual.

Bob Supnik	>Supnik@human.enet.dec.com
		>All opinions expressed are those of a hardline microcoder
		>and do not reflect those of Digital Equipment Corporation


From lasner@sunSITE.unc.edu Wed Apr 27 23:33:29 EDT 1994
Article: 778 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!sunSITE!lasner
From: lasner@sunSITE.unc.edu (Charles Lasner)
Newsgroups: alt.sys.pdp8
Subject: Re: 1's complement arithmetic
Date: 28 Apr 1994 03:29:20 GMT
Organization: University of North Carolina, Chapel Hill
Lines: 19
Message-ID: <2pnaig$pf5@bigblue.oit.unc.edu>
References: <2pht8o$3k7@sousa.amt.ako.dec.com>
NNTP-Posting-Host: calzone.oit.unc.edu
Keywords: 18b PDP's

Can't say about PDP-1, etc., but the LINC-8, LINC and PDP-12 all just 
allow -0 as 0.  So the AZE is skip on both 0 flavors.  However, APO only 
skips on +0.

Generally speaking, +0 never happens as an arithmetic result, just from 
clearing out something and then leaving it alone.

Additionally, the analog peripherals are actually two's complement.  A 
common display bug is calculating a display point that goes to the other 
end of the screen.  To correctly deal with it, you have to use the LAM 
instruction which is two's complement or use the -8 side if not an 
original LINC.

1's complement also screws up table lookups unless you are calculating an 
offset off of a non-zero base.  Thus tables are not generally placed at 
0000 in a memory segment!

cjl (Not carrying too many ends around!)


From jones@pyrite.cs.uiowa.edu Thu Apr 28 23:42:36 EDT 1994
Article: 779 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!corpgate!news.utdallas.edu!wupost!math.ohio-state.edu!hobbes.physics.uiowa.edu!news.uiowa.edu!news
From: jones@pyrite.cs.uiowa.edu (Douglas W. Jones,201H MLH,3193350740,3193382879)
Newsgroups: alt.sys.pdp8
Subject: PDP-8/E UNIX X-Windows Emulator
Date: 28 Apr 1994 14:15:01 GMT
Organization: University of Iowa, Iowa City, IA, USA
Lines: 18
Distribution: world
Message-ID: <2pogd5$d45@nexus.uiowa.edu>
NNTP-Posting-Host: pyrite.cs.uiowa.edu

I've cobbled together an X-windows user interface to my PDP-8/E emulator.
It looks and feels like the real front panel of a PDP-8/E.

I've only tested in on a color X display, so I don't know how it'll work
on a monochrome grey-scale display, and I suspect it'll do fairly poorly
on a black and white display.

It has problems -- I've never written a real X application before, but
it should work on most versions of X (I stayed away from things like
Motif that not everyone has access to).

The X interface takes a big chunk of memory to compile -- but if you have
X, you have big memory, so that ought not pose problems.

I'll E-mail it to anyone who wants it.

				Doug Jones
				jones@cs.uiowa.edu


From mbg@world.std.com Fri Apr 29 18:17:00 EDT 1994
Article: 780 of alt.sys.pdp8
Newsgroups: alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!news.duke.edu!eff!news.kei.com!world!mbg
From: mbg@world.std.com (Megan)
Subject: Re: My first PDP-8
Message-ID: <Cox5yH.H69@world.std.com>
Organization: The World Public Access UNIX, Brookline, MA
References: <25APR199418191014@siva.bris.ac.uk>
Date: Wed, 27 Apr 1994 13:11:04 GMT
Lines: 29

ard@siva.bris.ac.uk (PDP11 Hacker .....) writes:

>1) The machine contains an RX50 drive, PSU, and a motherboard flat in the
>bottom, like a rainbow. On the motherboard is a socketed chip labeled 6120, and
>some other 40 pin IC's, all labeled the same. I assume the former is the CPU
>(my Intersil databook is at home, and I don't remember seeing that chip in it,
>only the 6100. What's the difference?). Oh, and a 7201 (serial chip I think),
>6402's (UARTs), a 1793 (floppy controller), and a 8751 (microcontroller for the
>floppy controller?), along with some CRT control stuff. Is the CRT controller
>standard, and if so, where can I get a data sheet

>2) There are 3 (empty) 40 pin connectors on the front of the motherboard. what
>are these for, and does anyone know the pinout

>3) Is the monitor cable the same as a PRO/rainbow mono monitor cable. I got an
>LK201 and a VR201 with it, but no cable.

>4) I don't seem to have a boot disk. Anyway, the manuals seems to imply that
>the machine is a dedicated word processor. Where can I get a real OS boot disk
>from (free (preferably :-)), or commercial), and what OS do I run?

>5) Anything else you can tell me about this toy?

I'd like to ask similar questions about a DECmate III.  It appears to have
an RX50 and a hard disk (RD3x?)

					Megan Gentry
					Former RT-11 Developer


From historical@aol.com Fri Apr 29 18:18:53 EDT 1994
Article: 781 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!corpgate!news.utdallas.edu!wupost!udel!MathWorks.Com!solaris.cc.vt.edu!news.ans.net!hp81.prod.aol.net!search01.news.aol.com!not-for-mail
From: historical@aol.com (Historical)
Newsgroups: alt.sys.pdp8
Subject: the Historical Computer Society
Date: 27 Apr 1994 21:58:05 -0400
Organization: America Online, Inc. (1-800-827-6364)
Lines: 12
Sender: news@search01.news.aol.com
Message-ID: <2pn57d$mh0@search01.news.aol.com>
NNTP-Posting-Host: search01.news.aol.com

Hello, my name is David Greelish, president of the Historical Computer Society
and editor of "Historically Brewed" our bimonthly newsletter. "HB" is filled
stories of the people and machines which forged a revolution that changed our
lives as drastically as the telephone and the automobile. It's informative,
interesting and often humerous. Past articles have covered the history of the
GUI, Altair, Star Trek and its influence on the development of the personal
computer, Computer war stories, Kaypro Korner, Apple ][ history revisited and
more. Regular features include letters, book reviews, trading post, classifieds
and other resources for computer history buffs. We have not yet had any stories
about mini-computers, but would like to soon.  I am especially interested in
learning more about DEC and the PDP's. If you would like subscription info,
please e-mail me. Thanks!


From lasner@sunSITE.unc.edu Fri Apr 29 18:27:04 EDT 1994
Article: 782 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!sunSITE!lasner
From: lasner@sunSITE.unc.edu (Charles Lasner)
Newsgroups: alt.sys.pdp8
Subject: Re: My first PDP-8
Date: 29 Apr 1994 15:34:29 GMT
Organization: University of North Carolina, Chapel Hill
Lines: 155
Message-ID: <2pr9e5$p04@bigblue.oit.unc.edu>
References: <25APR199418191014@siva.bris.ac.uk> <Cox5yH.H69@world.std.com>
NNTP-Posting-Host: calzone.oit.unc.edu

In article <Cox5yH.H69@world.std.com>, Megan <mbg@world.std.com> wrote:
>ard@siva.bris.ac.uk (PDP11 Hacker .....) writes:
>
>>1) The machine contains an RX50 drive, PSU, and a motherboard flat in the
>>bottom, like a rainbow. On the motherboard is a socketed chip labeled 6120, and
>>some other 40 pin IC's, all labeled the same. I assume the former is the CPU
>>(my Intersil databook is at home, and I don't remember seeing that chip in it,
>>only the 6100. What's the difference?). Oh, and a 7201 (serial chip I think),
>>6402's (UARTs), a 1793 (floppy controller), and a 8751 (microcontroller for the
>>floppy controller?), along with some CRT control stuff. Is the CRT controller
>>standard, and if so, where can I get a data sheet
>
>>2) There are 3 (empty) 40 pin connectors on the front of the motherboard. what
>>are these for, and does anyone know the pinout
>
>>3) Is the monitor cable the same as a PRO/rainbow mono monitor cable. I got an
>>LK201 and a VR201 with it, but no cable.
>
>>4) I don't seem to have a boot disk. Anyway, the manuals seems to imply that
>>the machine is a dedicated word processor. Where can I get a real OS boot disk
>>from (free (preferably :-)), or commercial), and what OS do I run?
>
>>5) Anything else you can tell me about this toy?
>
>I'd like to ask similar questions about a DECmate III.  It appears to have
>an RX50 and a hard disk (RD3x?)

DECmate III doesn't have a hard disk.  However, you are describing a 
III+, which is a very different animal in a somewhat similar box.

With all of the recent inquiries about the DECmates, I guess it's time 
for a DECmate FAQ which focuses in on DECmate issues beyond those 
presented in Doug Jones' PDP-8 model FAQ.

Here's a thumbnail version.

DECmate I looks like a VT-100 with a few extra LED's on the keyboard.  
The standard model can't do anything without anything plugged in, but the 
standard configuration comes with RX02.  If you get either flavor of the 
dual USART serial interface (with or without the optional bit-stuff chips 
which allow SDLC, etc.) then you can make the otherwise bare box become a 
VT-100 which appears to not quite have all of the AVO option.  (14 lines 
in 132 column mode which is neither 12 as without or 24 as with.)

The standard version could be a pedestal-based RX02 pair, but in theory 
it was marketed also like the small -11 systems which had casters under a 
frame supporting RX or even RL drives.  There is even a quad RX02 (dual 
pair) version (I have it!).  A desk version could sit next to a cabinet 
holding RL02's if the RL278 option is present, etc.

There is no slushware, as all of the CP-memory routines are built-in.  
Only a handful of functions are implemented.

All RX02 and/or RL02-based PDP-8 software attempts to run here, as long 
as LPT: conventions of the VT-78 are assumed (as opposed to device 66; 
the VT-78 invented a new serial convention, but also supported the 
standard device 66 and even the weird -8/a variant parallel LA-180 
non-standard interface).  Of course all DECmates don't quite run -8 
software, but we've discussed that elsewhere, etc.

DECmate II shares the table-top box and overall configuration of the 
PRO-325 and Rainbow.  The standard machine comes with one pair RX50.  
Hard disk options are the RD51 controller plugged into the central slot 
connected to a variety of MFM drives which are meant to be housed in the 
top central area of the box.  Drives that were sold with the DM II were 
the 5 MB ST-506, 10 MB ST-412, and the 20 MB ST-225.  These were known as 
the RD50, RD51, and RD31 respectively.  Certain systems containing the 
ST-225 came with paperwork claiming they were only 10 MB, but customers 
quickly saw through this ruse.

As long as there isn't an MFM drive in the central area, an optional 
second RX50 pair can always be plugged in.

As long as there isn't a hard disk controller present, the RX78 option 
can be plugged in.  The RX78 can talk to one or two pairs of RX01/02/03.  
Cabling is via the standard connector associated with the DECmate I.  
(The documentation shows a DECmate I system being upgraded so that the 
pedestal of the RX02's holds up the DECmate II replacing the DECmate I box.)

All systems actually include three option slots, but the left (back view) 
is for the graphics option only while the right is for the APU or XPU 
options only.

There exist early systems incapable of supporting the graphics option, 
but this can be corrected by applying a substantial amount of hand 
soldering (add/deletes).  These systems also need a ROM upgrade to 
support the hard disk.  Many systems can only barely support the hard 
disk and should have the ROM upgraded to eliminate certain POST bugs.

The APU option is a Z80 and 64 KB memory.  It is used in a few WPS 
features and to run CP/M-80.  The XPU is a superset that also includes an 
8086 that is faster than the Rainbow and can be upgraded to a V30.  There 
are two memory options, 256KB and 512 KB.  The 512 KB version appears to 
have been able to support 1.0 MB but was never marketed as such.  Either 
version support the Z80 with some form of windowed memory sharing.  
MS-DOS 2.11 is available for the XPU versions.  (Note: IBM-PC 160 KB and 
180 KB diskettes are supported read-only on this system as well as the 
standard Rainbow MS-DOS format which is the same as the DECmate MS-DOS 
format.)

The graphics board comes in an early and late version.  Both are viable, 
but there are minor programming differences.  Most software 
self-configures around the differences, but some early diagnostics won't 
run on later boards.  (In any case, the option boards themselves are 
quite rare!)

The graphics board can talk to the normal mono monitor, and also 
supports the VR-241 color monitor as an option.  An obscure cable 
allegedly allows a color-only one monitor system.  (The WPS group claims 
that they won't support it, implying there is something to setup somewhere
that matters!)  In any case, the mono monitor can't have the text 
disabled, and the graphics interface can't have the color graphics output 
disabled.  All other video aspects can be gated to either output.  The 
GTE (Graphics Terminal Emulator) program exploits all of these modes, etc.

The DECmate III is housed in a small footprint box associated with the 
MicroVAX.  Early versions have marginal power supply problems.  Only an 
RX50 is present and there are no storage options.  There is an APU option 
that is compatible software-wise with that of the DM II.  There is also 
an optional graphics board that is quite rare.  Either of these can go 
into the two provided buss slots.  If the graphics board is present, then 
the color monitor is allowed; this is always a one-monitor system.  
Rumored to have been created but in any case never marketed is an 
MS-DOS-capable board that may have been a 286 and would have interfered 
with the VAXmate marketing.  There is also a special connector for a 
special version of the DEC Scholar 300/1200 Baud modem mounted internally.

The DECmate III+ superficially looks like the DECmate III, but uses a 
totally different board.  The mainboard supports a standard daughter 
board which is compatible with the RD51D hard disk option of the DM II.  
In the package is an RX33 TEAC floppy slowed down to be compatible with 
one/half of an RX50.  Also present is an RD31 or ST-225 20 MB MFM hard 
disk.  The external buss and slots are the same as in the DECmate III, 
and the same two options apply.

Clearly the board was meant to replace the DM III board since it can also 
be configured with a pair of RX33 drives and you can delete the hard disk 
daughter board.  Also the modem connector is present, but the associated 
chips aren't soldered in (but the lands are present!).

The developers of the never-marketed MS-DOS board reported that the 
ability to read the SDDD PC diskettes didn't work on the DM III+ because 
only the RX50 versions' controller supports this.


That's a short version.  If I work up a longer one, it'll get put on the 
sunsite archive, etc.

>
>					Megan Gentry
>					Former RT-11 Developer
>

cjl


From cczanj@vaxb.nott.ac.uk Sat Apr 30 00:19:06 EDT 1994
Article: 783 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!gatech!howland.reston.ans.net!pipex!lyra.csx.cam.ac.uk!warwick!unicorn.nott.ac.uk!vaxb.nott.ac.uk!CCZANJ
From: cczanj@vaxb.nott.ac.uk (Andy Jack)
Newsgroups: alt.sys.pdp8,comp.sys.dec
Subject: PDP8 commands?
Date: 29 Apr 1994 14:23:44 GMT
Organization: University of Nottingham, UK
Lines: 29
Message-ID: <2pr59g$odj@unicorn.ccc.nottingham.ac.uk>
Reply-To: cczanj@vaxb.nott.ac.uk
NNTP-Posting-Host: vaxb.ccc.nottingham.ac.uk
Xref: bigblue.oit.unc.edu alt.sys.pdp8:783 comp.sys.dec:19683

I have been asked to look at a problem in our Chemistry department where they
have not one but two PDP8's attached to ancient spectroscopy equipment. Sadly
the chemist who used this kit had a heart attack and died last month. Another
member of the department is trying to unravel how data was collected and
processed. 

One of the PDP8's has an RK05 disk and a Kennedy half-inch mag tape, and we
surmise that data from the spectroscopy stuff was written to disk and then
copied to tape which was then brought over here to the computing centre.

Our problem at the moment is that we cannot see *how* the copy to tape is done,
nor can we find a manual or any notes that would help. There is an old console
log taped to the side of the machine. It shows a program called MTPIP being
used and that is presumably a Mag Tape version of PIP which in turn must be a
fore-runner of the PDP-11 RT11/RSX PIP. 

The syntax is something like
	MK0:<DR0:FRED
which presumably copies a file called FRED from the disk to tape. There are
various switches /E, /Z etc. which baffle me.

Anybody got an old manual or a very long memory? Answers by mail please.

	Regards,
	Andy Jack
------------------------------------------------------------------------
Cripps Computing Centre,     RFC-822: Andy.Jack@nottingham.ac.uk
University of Nottingham,    X.400: G=Andy;S=Jack;O=Nottingham;P=UK.AC;C=GB
Nottingham NG7 2RD, UK	     Phone: +44 602 513328


From gsc@cairo.anu.edu.au Sat Apr 30 00:20:33 EDT 1994
Article: 784 of alt.sys.pdp8
Path: bigblue.oit.unc.edu!concert!xanth.cs.odu.edu!news.larc.nasa.gov!lerc.nasa.gov!magnus.acs.ohio-state.edu!math.ohio-state.edu!howland.reston.ans.net!agate!ihnp4.ucsd.edu!munnari.oz.au!newshost.anu.edu.au!cairo!gsc
From: gsc@cairo.anu.edu.au (Sean Case)
Newsgroups: alt.sys.pdp8
Subject: Re: 1's complement arithmetic
Date: 29 Apr 94 12:31:29 GMT
Organization: Australian National University
Lines: 14
Message-ID: <gsc.767622689@cairo>
References: <2pht8o$3k7@sousa.amt.ako.dec.com> <2pnaig$pf5@bigblue.oit.unc.edu>
NNTP-Posting-Host: 150.203.76.16
Keywords: 18b PDP's

lasner@sunSITE.unc.edu (Charles Lasner) writes:

>Generally speaking, +0 never happens as an arithmetic result, just from 
>clearing out something and then leaving it alone.

I take it this means the 1's complement PDPs didn't have a subtractive
adder. Why not?

Sean Case
--
Sean Case                  gsc@cairo.anu.edu.au

"November 11 - Ned Kelly died, ahh shame Fraser shame and we all cried."
        -- The Whitlams, "Gough"


From :supnik@human.enet.dec.com Tue May  3 08:46:59 EDT 1994
Article: 785 of alt.sys.pdp8
Newsgroups: alt.sys.pdp8
Apparently-to: BOB SUPNIK
Subject: 1's complement arithmeti
From:   :supnik@human.enet.dec.com
Path: bigblue.oit.unc.edu!concert!news.duke.edu!convex!cs.utexas.edu!uunet!cmpudata!  :supnik
Distribution: world
Message-ID: <12a.66.2370.0N3E1830@human.enet.dec.com>
Date: Fri, 29 Apr 94 03:05:00 -0400
Organization: -=- Compu-Data Information Services -=-
Lines: 37

  
BS>Message-ID: <2pht8o$3k7@sousa.amt.ako.dec.com>
BS>Newsgroups: alt.sys.pdp8


BS>    Did the 18b PDP's automatically convert -0 to +0 as part of (1's
BS>    complement) ADD?  There's a note to that effect in the ISP descripti
BS>    of the PDP-1 and PDP-4 in "Computer Engineering", but I can't find a
BS>    reference to this in the PDP-4 manual.

 Bob:
    If Ken and Gordie weren't held in such Wonderful regard over there, I'd 
say they're the best to answer the question. Having owned (and lost, sigh) a 
-7 -9 and -15, I believe the -1 and -4 were sort of the odd machines out of 
the series and handled things differently.
     Computer Engineering, Bell, et. al. says only the PDP-1 used ones 
complement arithmatic "therefore, the PDP-4 was designed to use two's 
complement arithmetic and to use the link bit from the Lincoln Laboratory 
L-1 design (p142- Bell/Butler/Gray/McNamara/Volinda/Wilson's Chap. 6.
     By the way - an urgent request to a decSter with some interest in 
history. Heard word DEC was moving out of the old Maynard Mills. Could 
someone PLEASE float the new corporate board the suggestion that the 
building be turned over to The Computer Museum and used to house operating 
old systems, as opposed to the new Computer Museum which has a collection 
that dates from the introduction of the 80484 these days!
     I'll even come up and help get the old beasts kicking if 
work/vacation/weekend time allows, and I'm sure several hundred others would 
join me.
                                                    
                                     [david.razler@compudata.com]
                                      (who carries an XX2247 key at all     
                                   times Never know when it might come 
                                        in handy)

[david.razler@compudata.com]
---
 * WaveRdr 1.0 [NR] * UNREGISTERED EVALUATION COP


