reg@vaxine.UUCP (Rick Genter) (04/12/85)
I have an IBM PC which I upgraded (via third party hardware) to an XT. I
upgraded the system about a year ago. I have 320K of memory. I have one
floppy (the one it came with). I have an AST+ card. I have a Sandstar disk
controller for my Maynard 10MB hard disk. I have an 8087 coprocessor. I am
running Venix 2.0.
The system ran fine for about 10 months except for the following problem:
if I left the cover on, invariably within a few hours it would display "Memory
Parity Error 1" on the screen and lock up. Only letting the thing cool down
for an hour or so would bring it back. Thus I took to leaving the cover off.
With the cover off it would run for weeks on end with no problem.
In January I moved from an apartment to a house. The temperature in the
house is about 15 degrees colder than it was in the apartment, so I thought I
would try putting the cover back on. I did this in the morning. When I got
home from work, there was the familiar Memory Parity Error 1. However, this
time it did not come back from the dead.
I tried removing the various boards from the system, and finally, in an
act of desperation, removed all the boards, removed the 8087, removed the
Maynard BIOS, configured the system to have 16K of RAM, no disk drives and
hoped it would boot into IBM cassette BASIC. I don't even get the reassuring
beep on power-up. I've checked the power supply (at the backplane) and all the
voltage levels are nice and solid. +5 is +5.0V. -12 is -12.0V.
From all of this, I have concluded that either my 8088 is dead, or the IBM
ROMs are dead. Thus the following questions:
*) Does my diagnosis sound at least partially correct? Or am I on
the wrong track?
*) If it turns out to be the 8088, I could just go out and buy another
one. If I do this, can I go out and buy an 8086 instead? (Are
they pin compatible?)
Please respond via mail. I will summarize to the net. Thanks in advance.
- reg
Rick Genter
Automatix Inc.
...!decvax!encore!vaxine!reg