Hurrah! Now time for some Doomin' on that board. 😎

Eep386 wrote on 2021-10-08, 19:45:

Hurrah! Now time for some Doomin' on that board. 😎

..that goes without saying buddy...
But I'm just happy to see it live again atm..
The guy who sold this board for cheap on ebay had more or less given up on it I think.
cheers..

So ..today I'm investigating the external cache on the gigabyte board..
Not something I have much experience with.
I have 9x 28 pin KM68257BP-20
..which I assume are 32k per chip so in total using one of the chips as TAG ...would allow me a total of 256k cache ..am I correct so far ?
and this of course assumes the chips are good ..and I have no way to test them individually.
My TL866 doesn't support this.
So..
I have 2 banks on the mobo 0 and 1
so I assume I fit all nine and then work out which jumpers to set..
If anyone knows this board ...I'd appreciate knowing the jumper configuration from someone who has actually used this motherboard...rather than just referring to the manual.
As it stands atm I see 64k cache at boot but then there are no jumpers fitted ..which I assume to be default with all jumpers open.
rgds
VS

So ..working on the assumption my reasoning was sound...I re-watched Necrowares youtube video pausing on closeups of the board...
His video confirmed my assumptions...so copied his jumper settings..
Looks good for 256k external cache.

Vipersan wrote on 2021-10-10, 14:20:

So ..working on the assumption my reasoning was sound...I re-watched Necrowares youtube video pausing on closeups of the board...
His video confirmed my assumptions...so copied his jumper settings..
Looks good for 256k external cache.

First I wanted to congratulate you on the excellent work, I don't know if you are a repairman or an hobbyist, in any case it is true that the experience helps, but sometimes the knowledge of what you want to repair also helps.
Returning to the 486 cards, in the first image (the one with the cache chips), you can see a silkscreen with the jumper settings for the amount of cache on board.
I don't know if they are currently set up like screen printing, if not so obviously there is an error.
The important thing is that the quantity present is correctly detected.
Perhaps a similar problem, I have it on a MB 486-Opti-VLB from Zida, the 128KB present are not detected, to start the PC I have to disable the L2 cache, otherwise by activating it the PC freezes on the second screen of the BIOS (the boot one).
Unfortunately I don't know if it is due to some bios setting, or a chip failure, I remember having expanded the capacity up to 256KB, then something happened, but the 128KB I added works (on another MB), maybe maybe it is the TAG chip that is causing the problem (I don't know), I should try to change it, but it is also true that turning off the cache 0KB is read, and therefore I would think that the TAG works, and maybe the four chips have problems.
Lately I have dealt with older PCs (see signature), plus I have recovered another one plus a couple of motherboards to be repaired, an Atronics 386DX-20 (from 1989) and a Zida 486VLB, some and others if you want to see them find here:
Re: Test and troubleshoot PC@LIVE motherboards

Another MB I worked on long ago is here:
Re: Identify motherboard Slot 1 SIS chipset
I'll try to review it shortly to see if I can solve it