80486 MoBo wont start with most EDO modules \ VOGONS

80486 MoBo wont start with most EDO modules

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First post, by Stojke

Posted on 2012-10-10, 19:33

Stojke Offline

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I have recently bought an 486 system from a flea market and inside it is a pretty decent system.

I wanted to upgrade the mother board with some memory, but it wont start or it says: Unknown-S CPU at 32MHz (its 80486 DX2 66MHz).

I tried multiple module pairs from 16MB to 32MB, but it wont start with any over 8MB and some i have no idea what their capacity is.

It only starts with 2 4MB modules i have and one 8MB module.

The mother board is CH-471B.

Reply 1 of 7, by luckybob

Posted on 2012-10-10, 20:55

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looks like this: http://stason.org/TULARC/pc/motherboards/C/CH … 86-CH-471B.html

It is a mistake to think you can solve any major problems just with potatoes.

Reply 2 of 7, by Stojke

Posted on 2012-10-10, 21:11

Stojke Offline

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Yes thats the thing. Ive kinda skipped trough it, saw the memory requirements, but i dont quite get it.

Whats the difference between x36 and x32?

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Reply 3 of 7, by luckybob

Posted on 2012-10-10, 21:13

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parity. x36 modules have 9 or 3 physical chips. (I've seen 5, but 95% are 9) x32 are non-parity. they have an even number, usually 8. some boards are parity only, but most don't care. it maybe your board cares.

It is a mistake to think you can solve any major problems just with potatoes.

Reply 4 of 7, by Stojke

Posted on 2012-10-10, 22:45

Stojke Offline

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Well, the modules that work are all 8 chips. As you said paired.
At one point i thought it was the CPU thats the problem, or some jumper settings...

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Reply 5 of 7, by swaaye

Posted on 2012-10-11, 00:23

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You need fast page mode SIMMs instead of EDO SIMMs. EDO doesn't work with most 486 chipsets.

Reply 6 of 7, by luckybob

Posted on 2012-10-11, 00:30

luckybob Offline

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swaaye wrote:
You need fast page mode SIMMs instead of EDO SIMMs. EDO doesn't work with most 486 chipsets.

you know, I had just thought of that. now "SOME" edo chips are backwards compatible. I have a 64mb set. In fact it runs my mac 660av. That would explain why some "edo" modules work and some don't.

I believe the umc8881 is the only chipset to actually support edo.

It is a mistake to think you can solve any major problems just with potatoes.

Reply 7 of 7, by nforce4max

Posted on 2012-10-11, 00:55

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You are better off sticking with those 4 and 8mb modules. I have gotten some to work with EDO that were generic boards but it is hit or miss. OEM machines have the best support when it comes to ram but boards like this can be difficult.

On a far away planet reading your posts in the year 10,191.

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