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Parity check

evildragon

Veteran Member
Joined
May 29, 2007
Messages
1,646
Location
Tampa Florida
Oh boy, I think my IBM is nearing it's demise.

I went to turn it on, and it started booting, and when it was connecting to a NTP server to set the clock, the entire screen went blank with this on it:

parity.jpg


So I turn it off, wait a minute, turn it on, and I kept getting this:

mem.jpg


I then turned it off, frustrated.. The memory lasted all these years and now it's dying. At this point, I'm thinking I killed the freaking thing with that Bad Apple demo I made a couple weeks ago. So now I feel I'm a bad programmer and pushed the hardware too far that it actually killed the memory, as that demo was literally, the hardest thing this IBM has EVER played.

So a couple hours passed, and I tried turning it on again, now it's booted up nice and fine. So I ran PC-Check on it and did a thorough memory test, and it passes now.

What the!? The memory was failing, now it's fine?
 
You're not a farmer are you? ("Parity check" - what a farmer gets from the government for not raising corn) :)

It could be a wonky power supply that's causing this (check your voltages). Otherwise, keep a log of the reported failing locations. Right now, it doesn't look like a genuine memory error.
 
Ok I'll keep a watch on it.

Isn't this what the power good signal is supposed to do though? The power supply levels out and tells the motherboard things are good to go?
 
Not completely, all it does is tell if the PSU is okay.
If it is not there at boot it will reset the CPU if it falls below spec it shuts down the CPU during operation.

Again this is taking the PSU's word for it that it's OK.

On the board of the computer this can be a different story. ;)
 
Ok I'll keep a watch on it.

Isn't this what the power good signal is supposed to do though? The power supply levels out and tells the motherboard things are good to go?

PG is a very poor indicator. It's supposed to be raised when power supply levels are stable. Usually, it's something simple, such as a time delay circuit or comparator.
 
I just noticed something strange here.. When I type "mem" at DOS, it says I have 638KB conventional memory.

Uhhhhhhh? Where'd did the 2KB go?! The BIOS counts to the full 640KB and passes POST test.
 
Last edited:
I just noticed something strange here.. When I type "mem" at DOS, it says I have 638KB conventional memory.

Uhhhhhhh? Where'd did the 2KB go?! The BIOS counts to the full 640KB and passes POST test.
This isn't a new machine -- you've had it some time, right? And, it always had 640K before when you typed mem. A boot sector virus or other bad boy could cause this. I know I've seen malware reduce the 640K to 639K at boot and I'm not familliar enough with all the parasites to remember their specifics but it's probably worth looking into.
 
This isn't a new machine -- you've had it some time, right? And, it always had 640K before when you typed mem. A boot sector virus or other bad boy could cause this. I know I've seen malware reduce the 640K to 639K at boot and I'm not familliar enough with all the parasites to remember their specifics but it's probably worth looking into.

I've had the computer since my birth.

Boot sector virus wouldn't affect ROM BASIC.
 
Gah! It passed another test of PC Check, then went to a black screen with:
PARITY CHECK 1
00000(S)

Then when rebooted, passes POST again.

I'm going to remove ALL cards, modules, etc, and do a thorough cleaning.
 
Reseated the memory, and went to load compushow to load a picture and got a Stack Overflow, System Halted.. Control alt delete does NOT work, everytime these errors come up.

I even reseated the expansion cards.

Didn't measure power supply levels yet.
 
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