Path: utzoo!attcan!uunet!dalcs!lane
From: lane@dalcs.UUCP (John Wright/Dr. Pat Lane)
Newsgroups: comp.sys.ibm.pc
Subject: Why am I getting this crazy parity interrupt???
Message-ID: <2968@dalcs.UUCP>
Date: 7 Aug 88 08:43:44 GMT
Distribution: na
Organization: Math, Stats & CS, Dalhousie University, Halifax, NS, Canada
Lines: 36

Perhaps some tech expert out there can tell me what's wrong with my system,
a locally built AT clone (6/10MHz 286, 1Meg RAM, herc clone video, Western
Digital disk controller, Panasonic 1.2Meg floppy, ST-225 hard disk).  I'm
using PCDOS 3.20.  Here's the problem:

I get an occasional but frequent memory parity interrupt at location F000:ADF1.
It always occurs while doing a floppy disk access.  It's never caused a problem
other than the interruption and I've never detected any corruption of the file
being read or written. I have one of those little TSR parity interuppt handlers
installed so it's just a persistent annoyance.  What really strikes me strange
is that the address given (by DOS's parity interrupt handler) is in ROM which
was, I thought, not parity checked?!?.

Another wrinkle: I have a ram-disk (VDISK) as drive E: and on the next access
to it after getting the floppy-disk parity error I always get a Data Error.
I always tell it to re-try and everthing is just dandy.  Weird, eh?


There are some related problems that only occur on the faster CPU speed:

Certain pop-up TSR programs cause DOS to report a memory parity error in low
memory when popped-up.  Again, It doesn't seem to cause any problem beyond the
interruption.

Ceratin graphics programs cause the video to go bannanas (a pattern appears 
that looks like a flock of seagulls and slowly expands on the screen and which 
point I nervously re-boot).  The programs work fine at the slower speed and 
other graphics programs work at all speeds.

Any tips/hints/clues much appreciated.

-- 
John Wright      /////////////////     Phone:  902-424-3805  or  902-424-6527
Post: c/o Dr Pat Lane, Biology Dept, Dalhousie U, Halifax N.S., CANADA B3H-4H8 
Cdn/Bitnet: lane@cs.dal.cdn    Arpa: lane%dalcs.uucp@uunet.uu.net
Uucp: lane@dalcs.uucp or {uunet,watmath,utai,garfield}!dalcs!lane