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486 cache trouble shooting ?

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First post, by Intel486dx33

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The cache on my 486dx2-66 motherboard is NOT working.
It does not register with the computer.
Originally this motherboard came with 64kb.
but it is upgradeable to 256kb.
So I inserted some cache chips ( 8 chips )
and 1 tag chip.
They read 265 and -15ns.

But they do not register with the motherboard.
I set the jumpers correctly.
The TAG chip is a bit longer than the other 8 chips.
but it reads 256 and -15ns
I tried a regular cache chip there to and it still would not register.

My question is how can I go about trouble shooting this problem?

I want to know if I remove 1 cache chip at a time and test with CACHECHK program
will this method work?
Will it work with 1 chip removed ?
Or do I need all 8 chips plus the TAG to be installed in order to test the cache amount ?
I suspect some of my cache chips may be bad or damaged ?
The only tool I have for checking electronics is a Multimeter.

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Reply 1 of 10, by Vynix

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It's possible that you somehow got fake cache chips...

Proud owner of a Shuttle HOT-555A 430VX motherboard and two wonderful retro laptops, namely a Compaq Armada 1700 [nonfunctional] and a HP Omnibook XE3-GC [fully working :p]

Reply 2 of 10, by Intel486dx33

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Vynix wrote:

It's possible that you somehow got fake cache chips...

Well that's what I want to know.
Do you know how to test these chips with a multi-meter ?

Reply 5 of 10, by Vynix

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Try to run CACHECHK, it should (keyword here is "should", it's not a surefire way to determine, I've seen some 486es being a bit skittish with cache).

Also if these chips that you bought have a suspicious looking writing on them (E.G. if it easily scrapes off), that's another finger pointing at them being fake. There's been fake clones of ISSI cache chips floating around...

Proud owner of a Shuttle HOT-555A 430VX motherboard and two wonderful retro laptops, namely a Compaq Armada 1700 [nonfunctional] and a HP Omnibook XE3-GC [fully working :p]

Reply 6 of 10, by Intel486dx33

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So if I remove all the cache chips but one and leave the TAG installed. I can check each cache chip individually to see if it's good using "cachechk" program ?

Will this method work ?

Reply 7 of 10, by Vynix

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Well, I suppose it should work, I haven't looked much into CACHECHK (I don't have any system that takes cache chips for L2 cache), so I don't know how it'll behave

Edit: Scratch that. See Tiido's reply.

Last edited by Vynix on 2019-11-22, 01:05. Edited 1 time in total.

Proud owner of a Shuttle HOT-555A 430VX motherboard and two wonderful retro laptops, namely a Compaq Armada 1700 [nonfunctional] and a HP Omnibook XE3-GC [fully working :p]

Reply 8 of 10, by Tiido

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That will not work, at best you have instant crash when BIOS tries to enable cache. Entire bank needs to be present, just like with RAM.

T-04YBSC, a new YMF71x based sound card & Official VOGONS thread about it
Newly made 4MB 60ns 30pin SIMMs ~
mida sa loed ? nagunii aru ei saa 😜

Reply 9 of 10, by Intel486dx33

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Okay, I took out the motherboard to get a better look at the cache.
It looks like one of the cache chip legs might have not been making contact.

So I reinserted all of them carefully checking to make sure they are inserted properly.

Now I have a question.

I have to select which chip to use for TAG.
I have two chips.
One is the same as all the other cache and is labeled Alliance 256
The other one is longer and is labeled ANSI 512.

Which one should I use ?

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Reply 10 of 10, by Intel486dx33

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Okay, I checked and re-seated the cache chips and tried both types of TAG chips and it still will NOT register with my bios.
So they are NOT working.
I double checked the jumpers and they are correct.

Any ideas what maybe wrong ?

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