A bit of an update.

Got a ST HP93L9244 (22pin) in the hope that it would work, but alas no cache is detected.
(I was wrong in first post, it is a 22 pin socket)

I tried getting 128Kb cache to work as I managed to put 1 of the UM61 chips in the wrong way, and now it gets very hot if I try to use it.
So that one is broken.

Still no L2 cache is detected.
So unless somebody knows what chips to use, I will have to give up on this.

A pity, as I really wanted to squeeze as much performance as I can out of the system.

Does this help.

Check here:
http://ps-2.kev009.com/pcpartnerinfo/ctstips/c776.htm

Not looked at that link before, but doesn't appear to be the same type as what I have.

I have looked at https://stason.org/TULARC/pc/motherboards/I/I … -6482-6484.html as it is a 6482 I have.

Here there is 2 Tag chips. One seems to be the same as the cache chips.
The same as the link you provided, but there is also a 22pin one that has unknown specifications.

Another site I have looked at is http://ps-2.kev009.com/pcpartnerinfo/ctstips/86ae.htm This mentions you need 9x28 pin for 256Kb cache, and 1x22 pin Tag ram.
It does list the Ibm part numbers, but not the specifications for them.

I think the 22 pin one is the key, to get the bios to recognize the cache ram.
But what type of chip I need, has eluded me.

That 22pin chip is probably one of the special TAG RAM chips such as IDT6178S

Yes, Should be jumpers 9 & 10

CACHE JUMPER CONFIGURATION

J9 , J10

128KB
Pins 1 & 2 closed
Pins 1 & 2 closed

256KB
Pins 2 & 3 closed
Pins 2 & 3 closed

To upgrade from 128KB cache to 256KB, you need to add four 28-pin modules (32K x 8, 25ns SRAM) and replace the existing TAG module with one 28-pin TAG (32K x 8, 20ns SRAM).
To upgrade from 0KB cache to 128KB or 256KB, you need to add either 4 (for 128KB) or 8 (for 256KB) 28-pin modules (32K x 8, 25ns). You also need to add a TAG module (32K x 8, 20 ns SRAM for 256KB or 8K x 8, 20 ns SRAM for 128KB)
Cache memory jumpers are preset at the factory for 0/128KB of cache. If you are installing 256KB, reset the jumpers by moving them forward to cover the two jumper pins.

I think I have done it correctly,regarding setting jumpers and so on, it's the 22 pin tag I think is the problem.

Did a quick search on ebay, and got 3 hits for IDT6178S.
One (and it had to be the cheapest one) has the wrong form factor, but I may try my luck with one of the others-

Good luck. Good to know because I am thinking about upgrading the cache on my IBM PS/1 Valuepoint too.
Keep us informed. First I am going to update the CPU with Intel Overdrive 486dx-66mhz.
I like these Value point IBM’s because they are mostly non-proprietary parts and easy and cheap to upgrade and fix. Unlike the IBM computers with Proprietary parts mainly the IBM PS/2’s and older.

Still not decided if I try or not.

Apart from the cache part 😒 , I agree that the Value Point is much better to live with than PS/2 probably is.
Never owned one my self, but have seen Youtube videos on it.

If I decide to go for it, it probably will take some time as shipping is usually not fast.

I did end up buying one of the IDT6178S I found on ebay.

It did not work, and as long as it was installed, the computer refused to boot.