


      300(1)                        (DWB)                        300(1)



      NAME
           300, 300s - handle special functions of DASI 300 and 300s
           terminals

      SYNTAX
           300 [ +12 ] [ -n ] [ -dt,l,c ]

           300s [ +12 ] [ -n ] [ -dt,l,c ]

      DESCRIPTION
           The 300 command supports special functions and optimizes the
           use of the DASI 300 (GSI 300 or DTC 300) terminal; 300s
           performs the same functions for the DASI 300s (GSI 300s or
           DTC 300s) terminal.  It converts half-line forward, half-
           line reverse, and full-line reverse motions to the correct
           vertical motions.  It also attempts to draw Greek letters
           and other special symbols.  It permits convenient use of
           12-pitch text.  It also reduces printing time 5 to 70%.  The
           300 command can be used to print equations neatly, in the
           sequence:

                neqn file ... | nroff | 300

           WARNING:  if your terminal has a PLOT switch, make sure it
           is turned on before 300 is used.

           The behavior of 300 can be modified by the optional flag
           arguments to handle 12-pitch text, fractional line spacings,
           messages, and delays.

           +12      permits use of 12-pitch, 6 lines/inch text.  DASI
                    300 terminals normally allow only two combinations:
                    10-pitch, 6 lines/inch, or 12-pitch, 8 lines/inch.
                    To obtain the 12-pitch, 6 lines per inch
                    combination, the user should turn the PITCH switch
                    to 12, and use the +12 option.

           -n       controls the size of half-line spacing.  A half-
                    line is, by default, equal to 4 vertical plot
                    increments.  Because each increment equals 1/48 of
                    an inch, a 10-pitch line-feed requires 8
                    increments, while a 12-pitch line-feed needs only
                    6.  The first digit of n overrides the default
                    value, thus allowing for individual taste in the
                    appearance of subscripts and superscripts.  For
                    example, nroff half-lines could be made to act as
                    quarter-lines by using -2.  The user could also
                    obtain appropriate half-lines for 12-pitch, 8
                    lines/inch mode by using the option -3 alone,
                    having set the PITCH switch to 12-pitch.

           -dt,l,c  controls delay factors.  The default setting is



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      300(1)                        (DWB)                        300(1)



                    -d3,90,30.  DASI 300 terminals sometimes produce
                    peculiar output when faced with very long lines,
                    too many tab characters, or long strings of
                    blankless, non-identical characters.  One null
                    (delay) character is inserted in a line for every
                    set of t tabs, and for every contiguous string of c
                    non-blank, non-tab characters.  If a line is longer
                    than l bytes, 1+(total length)/20 nulls are
                    inserted at the end of that line.  Items can be
                    omitted from the end of the list, implying use of
                    the default values.  Also, a value of zero for t
                    (c) results in two null bytes per tab (character).
                    The former may be needed for C programs, the latter
                    for files like /etc/passwd.  Because terminal
                    behavior varies according to the specific
                    characters printed and the load on a system, the
                    user may have to experiment with these values to
                    get correct output.  The -d option exists only as a
                    last resort for those few cases that do not
                    otherwise print properly.  For example, the file
                    /etc/passwd may be printed using -d3,30,5.  The
                    value -d0,1 is a good one to use for C programs
                    that have many levels of indentation.

                    Note that the delay control interacts heavily with
                    the prevailing carriage return and line-feed
                    delays.  The stty(1) modes nl0 cr2 or nl0 cr3 are
                    recommended for most uses.

           The 300 command can be used with the nroff -s flag or .rd
           requests, when it is necessary to insert paper manually or
           change fonts in the middle of a document.  Instead of
           hitting the return key in these cases, you must use the
           line-feed key to get any response.

           In many (but not all) cases, the following sequences are
           equivalent:

                nroff -T300 files ...   and   nroff files ... | 300
                nroff -T300-12 files ...   and   nroff files ... |
                300 +12

           The use of 300 can thus often be avoided unless special
           delays or options are required; in a few cases, however, the
           additional movement optimization of 300 may produce better-
           aligned output.

           The neqn names of, and resulting output for, the Greek and
           special characters supported by 300 are shown in greek(5).

      SEE ALSO
           450(1), eqn(1), nroff(1), tbl(1).



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      300(1)                        (DWB)                        300(1)



           In ROS Reference Manual, graph(1), mesg(1), stty(1),
           tabs(1), tplot(1), and greek(5).

      BUGS
           Some special characters cannot be correctly printed in
           column 1 because the print head cannot be moved to the left
           from there.
           If your output contains Greek and/or reverse line-feeds, use
           a friction-feed platen instead of a forms tractor; although
           good enough for drafts, the latter has a tendency to slip
           when reversing direction, distorting Greek characters and
           misaligning the first line of text after one or more reverse
           line-feeds.










































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