AT Woes

[Tom Frauenhofer]

I'm having (what I believe are) hardware problems with my "homebrew" AT
system that I use to run Microport V/AT.  I wonder if someone might have some
ideas as to what is happening.

Hardware Configuration:
	"Baby AT" 8 Mhz 286 Motherboard w/ Phoenix Bios rev 2.10
		(Made by Computer Products United, it's 2 years old)
	1 Meg memory on board (512K of 41256-150 chips, 512K of 41256-120 chips)
	2 Hard drive: Seagate ST-251, Seagate ST-225
	1 1.2M floppy, 1 360K floppy
	Everex Floppy/Hard controller card
	2-port serial board with parallel port and game card
	Hercules mono clone with parallel port
	MCT-AEMS memory board with 512K on board (512K of 41256-150 chips)
	200 W Power Supply

Problems:

	1) I will (occasionally) get the error "NMI in system mode" on
	   the console.  The system doesn't crash, I can act as if
	   nothing happened, but obviously something did.

	2) Memory is configured as 512K standard, 1024K extended.  Occasionally
	   I get an error during boot where the 1024K extended segment only
	   shows up as 576K (I get an error message where it claims to reset
	   the segment, and it asks me to please run the setup program).

	3) Occasionally I will have a problem where the monitor screen
	   screws up (the text lines on the screen are no longer sequential -
	   they will be scattered all over the screen, and some of them start
	   about 40 characters over from the left margin), and the serial
	   ports hang.  I replaced the graphics card and disabled the printer
	   on the card, but it still happens.  It appears to only happen on
	   days when the room gets hot (when its 80+ degrees outside - the
	   room is on the 2nd floor of our house, and it gets pretty hot
	   up there).


Problem (3) I have been experiencing for over a year (didn't get hit by it
at all during fall time or the winter).  Problems (1) and (2) I've just started
to experience in the past week.  I should add that in the past week I've
re-formatted my ST-225 to use 15M of it for UNIX (I used to have it dedicated
entirely for DOS, but I haven't used DOS in the past year, so I decided I
could use that space more productively).  I also added the MCT-AEMS memory
board about 4 weeks ago.  I don't know if I'm having a power problem, if
I'm having a problem with the memory board, or if the configuration I've
got may be triggering a problem in the motherboard.  The NMI is a might
disturbing to me, let me tell you.

Thanks for any help you can give me.  If I had the money, I'd chuck the
system and get myself a decent 386 box (or at least replace my motherboard),
but I'm not that flush at the time, so I've got to make do with what I've
got.

Thomas V. Frauenhofer	...!rutgers!rochester!cci632!ccird7!tvf
*or* ...!rochester!cci632!ccird7!frau!tvf *or* ...!rochester!rit!anna!ma!tvf1477
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