Path: utzoo!attcan!uunet!mcvax!botter!klipper.cs.vu.nl!beugel
From: beugel@cs.vu.nl (Beugel BJ)
Newsgroups: comp.sys.ibm.pc
Subject: Problem with disk I/O in turbo mode
Keywords: parity check error
Message-ID: <1050@klipper.cs.vu.nl>
Date: 10 Jun 88 10:58:08 GMT
Organization: V.U. Informatica, Amsterdam, the Netherlands
Lines: 61


I am having a very strange and annoying problem with my XT
while doing disk I/O with large files in certain programs. Any
help will be much appreciated. Please mail me any answers rather
than posting them.


My system is configured as follows:

One IMC PC/XT with
- 4.77/8 MHz (Turbo) NEC V20 CPU;
- 640 K, 150 ns, parity checked main memory;
- 2 x 360 K floppy drives;
- 20 M, 65 ms Tandon hard-disk TM 262 with 3 sectors interleave;
- Western Digital WD 1002A-WX1 hard-disk controller;
- Hercules compatible display adapter with 1 parallel printer port;
- Multi I/O card;
- ANTEX BIOS;
- DOS 3.1

The problem is as follows:

In slow 4.77 MHz mode I have no problems whatsoever.
In 8 Mhz turbo mode however, the system hangs when I
try to save or copy a large file (e.g. 140 K) on the
hard-disk from within WordPerfect.
The screen is cleared except for an error message
saying "PARITY CHECK 200000 (S)" which is obviously not a
WordPerfect message but a BIOS message. After this the system
hangs completely. Even Ctrl-Alt-Del won't work.
Sometimes the system hangs without showing any error message.
My WordPerfect makes a backup of the file being edited every 15
minutes and this also hangs the system.
While copying files on the hard-disk with the DOS COPY-command
I have no problems.
Another program that hangs the system in exactly the same way
is PK(X)ARC. It hangs the system while archiving or extracting
large files on the hard-disks.
Both WP and PK(X)ARC seem to have no problems with small files.
Saving, copying, extracting and archiving files on one of the
floppy drives works fine too.

I have a program to test memory and my memory passes all the tests
both in slow and turbo mode.
I pulled out the memory chip that stores the parity bits of the
lower 256 K which resulted in the above mentioned error message when I
booted the computer. When I pull out the same chip for the next 256 K
the system boots fine but when I run the memory test the message
"PARITY CHECK 240000 (S)" appears. Obviously the message will
only appear when the corresponding memory is being addressed.
I exchanged all the chips for the lower 256 K with the ones for
the next 256 K but nothing changed.

If anyone has any ideas or suggestions please let me know.

Thanks in advance,

Berend Jan Beugel (beugel@cs.vu.nl via mcvax).


Bye bye!