 
                           PARITY ERRORS


  This QEMM 7 technote is an abridged version of a technical
  bulletin that is available through our standard support channels.
  If you are interested in a lengthier discussion of this subject,
  you can obtain the unabridged version from the following sources:

  Quarterdeck Technical Support BBS:  PARITY.TEC
                         CompuServe:  PARITY.TEC
                              Q/FAX:  #128


  Subject: An explanation of hardware PARITY ERRORS and suggestions
  for finding and correcting the problem.

  PROBLEM:   Since installing QEMM on your computer system you are
             getting "parity errors."

  CAUSE:     Parity errors are indicative of a hardware problem.

  SOLUTION:  Have the hardware components of your PC examined to
             determine where the problem lies.

  HOW DO I DETERMINE WHICH PIECE OF HARDWARE IS CAUSING THE PROBLEM?

  The first thing to check is the RAM in your system.  An easy test
  is to disable everything that uses EMS and XMS memory so you can
  create a RAMDRIVE the size of all your system memory.  (Refer to
  your DOS manual for information on creating a RAMDRIVE.)  Then:

     a) Run CHKDSK on the RAMDRIVE, or
     b) Copy files to the RAMDRIVE until it is full.

  Either way, eventually you will get a parity error or a General
  Drive Failure on the RAMDRIVE.  The first thing you can do to try
  to remedy this problem is to make sure that the RAM chips are
  seated properly in their sockets.  If they are DRAMs or SIPPs
  make sure the pins aren't broken off or bent.  If they are SIMMs
  or the memory is on a card, you may just need to clean the
  contacts.  If the chips physically check out ok, the chip speeds
  could be mismatched with memory that is too slow for the
  CPU/memory bus, or a controller chip could be bad.  At this point
  the only sure way to test this is to swap out the chips for ones
  that you know are good.

  Parity errors may also be caused by the presence of an
  autoswitching video card or one that is using 16-bit ROM access.
  Your motherboard could be assigning parity to the address space
  where your EMS page frame is located. Also there may be some
  special features of the computer in the CMOS Setup that could be
  causing problems.  Try disabling the computer's shadowing of BIOS
  or video ROM or turning off memory caching or other features to
  see if one of them is involved.  This may allow you to pinpoint
  the cause of the problem. In all these cases you should refer to
  the documentation that came with your hardware product to disable
  a particular feature.

  While there are several diagnostic programs on the market that
  will test your memory for errors, they may not duplicate
  conditions that would cause marginal memory to fail, and most are
  not even designed to be run with a memory manager.  When parity
  errors are encountered, it is time to have the hardware
  components of the machine examined.

  For a longer, more technical explanation of parity errors, refer
  to our unabridged technical bulletin (with the same filename)
  which is available through our standard support channels.  See
  CONTACT.TEC (in your QEMM\TECHNOTE directory) for information on
  obtaining technical bulletins.

  *****************************************************************
            Trademarks are property of their respective owners.
   This technical note may be copied and distributed freely as long
  as it is distributed in its entirety and it is not distributed
  for profit.  Copyright (C) 1993 by Quarterdeck Office Systems
  ****************** E N D   O F   F I L E *************************