What MB is this? \ VOGONS

What MB is this?

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First post, by lesliespinner

Posted on 2025-10-05, 20:20

lesliespinner Offline

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Does anyone maybe know which board this would be? It is IBM Pc-Server 300, type 8640, model CNT, with socket 3, 486 dx2 66mhz. L2 cache isn't working and I cant find any circut diagrams and such information... I did manage to reflash bios, but it didn't do anything. Now all eight sram chips have 5.15V, four integrated and four dip type, but this is where my little project is being halted. OS does boot, if I turn l2 off.

Reply 1 of 4, by jakethompson1

Posted on 2025-10-05, 20:54

jakethompson1 Offline

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If that is the tag ram up by the coin cell, 70 ns is much too slow.

Reply 2 of 4, by Horun

Posted on 2025-10-06, 01:29

Horun Offline

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Agree ! Cant read the main cache chips but guessing they are 15nS (or maybe 20nS)....

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 3 of 4, by Ozzuneoj

Posted on 2025-10-06, 01:42

Ozzuneoj Offline

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Looks like this Micronics M4Pe (09-00213-xx):
https://theretroweb.com/motherboards/s/micron … 4pe-09-00213-xx

The user manual available there seems to be for a different revision with a different layout, but the "MTL Jumper manual" seems to be the right one for your board. Sadly, neither one makes any mention of the possible TAG cache socket the others have mentioned above.

Now for some blitting from the back buffer.

Reply 4 of 4, by lesliespinner

Posted on 2025-10-07, 10:39

lesliespinner Offline

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Thank you all for pointing out the tag-ram. Yes, csche cjips are 15ns, two columns of four chips, one column integrsted. I can choose 128kb or 256kb, buth neither option works. I will take a look into the tag-ram. I think I should find a spare on some other board, but I've read a little about it having to have a proper size in ratio to l2 size... it could be, I've messed something there while working on rtc chip.

Luckly I have jumper settings printed on top of the tower, I will take a picture and post it in the evening. I did try all possible cache combinations and ws1 and it doean't work.

Layout is indeed different, but at least I have a pointer to which company mb is from. I found out that pcserver 300 pentium is confirmed Micronics, so 99% this one is too. Thank you all for the goodwill and time, I will post what I found out with the tag-ram

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