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L2 cache not getting all 256KB, rather 32KB only

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First post, by bjwil1991

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I have a PC Chips M912 V1.7 board with real L2 cache and when I got everything installed, the cache is being seen as 32KB cache instead of 256KB cache. I installed the DX4-100 OverDrive set to 5VDC, FSB 33MHz, Clock multiplier 3x, and nothing. All of the jumpers are correct according to the manual (cache option C) and everything is seated correctly.

The board has 16MB RAM installed, VLB I/O card, Trident ISA VGA card, and has a mix of ASD and Toshiba 32Kx8 (256Kb) SRAM chips of the same speed of 15ns.

Manual photo:

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I checked the board for any damage and none were found, except for the CPU clamp lever that was broken (replaced it and works without issues), but otherwise in good shape.

I'll post photos of the cache and current jumper configuration and maybe even change the jumper around for the BIOS chip and see if that does anything, which might not, however, who knows?

Discord: https://discord.gg/U5dJw7x
Systems from the Compaq Portable 1 to Ryzen 9 5950X
Twitch: https://twitch.tv/retropcuser

Reply 1 of 6, by Horun

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You might want to look at my post earlier today about M912 v1.7 in Retro activities. There are some pics with the jumper settings for diff cache setups and what cache chips came with the boards originally (afaik)
Re: What retro activity did you get up to today?
They all report 256k cache and boot properly . If running only one cache bank you need to change the BIOS settings by disable "auto" and set read to 3-2-2 -2. Edit: as stated in that pic you posted.

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 2 of 6, by bjwil1991

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Well fuck me. JP36 was missing the jumper. After installing it, it gets all 256KB. I looked in the jumpers.html file and there it is.

Discord: https://discord.gg/U5dJw7x
Systems from the Compaq Portable 1 to Ryzen 9 5950X
Twitch: https://twitch.tv/retropcuser

Reply 3 of 6, by Horun

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Great ! Had an issue with the one board with just one bank and it was also a jumper issue. Good Work !
added: Can you post a picture of your board ? Just curious as there were many minor variations between them.

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 4 of 6, by bjwil1991

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Pictures of the board (eBay photos):

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s-l1600-cache.jpg
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s-l1600-cache.jpg
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The CPU lever has been replaced without issues, except for brittle plastic pieces on the CPU socket (top one), but I had a spare anyway from the beyond repair board. Building an old computer or bringing back childhood memories from back then is fun (somewhat). Planning on getting a Diamond Stealth 32 (TSeng ET4000/w32p) VLB card to replace the Trydon't VGA card (will be used in another project or to test the ISA slots in another computer).

Discord: https://discord.gg/U5dJw7x
Systems from the Compaq Portable 1 to Ryzen 9 5950X
Twitch: https://twitch.tv/retropcuser

Reply 5 of 6, by Horun

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bjwil1991 wrote on 2020-04-12, 05:52:

Pictures of the board (eBay photos):

Wow really Nice ! That is an original PC Chips sold board, not a rebranded one from Amptron or PerComp. The black ISA and brown VLB slots plus the AMI BIOS are the tell tale signs afaik. That BIOS should be Y2K ok, the Award one was not. They are very good 486 boards except for all the jumpers hahaa.

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 6 of 6, by bjwil1991

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I had a board similar to this one, except it had the Award lawsuit BIOS and the BIOS chip stopped working (never kept the time and date correct and always lost the settings). Too bad I didn't keep the board so that I could fix the BIOS issues by writing a BIOS to it, but I didn't have the tools or chips at hand in 2012 as the USB programming tools were a bit expensive back then. Fortunately, I backed up the BIOS in case it goes out the door, at least I can fix it by programming it to a new one.

The AMI WinBIOS is really cool looking, but my mouse doesn't work with it for some reason (mouse works in DOS and Windows, but not the BIOS).

Discord: https://discord.gg/U5dJw7x
Systems from the Compaq Portable 1 to Ryzen 9 5950X
Twitch: https://twitch.tv/retropcuser

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