H3llR4iser wrote on 2025-09-16, 16:54:

Hi folks, […]
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Hi folks,

I just got the motherboard in question - as per title, a Jetway J-435B; It works quite well, but I've noticed something odd - while it reports having 256KB of cache, both SpeedSys and Cachecheck only detect 128KB usable.

Now, my board looks almost exactly the same as the one pictured on the Retroweb -> https://theretroweb.com/motherboards/s/jetway-j-435#docs - Actually suspiciously the same, to the point is also has that weird two different tone cache chips AND even the date codes are exactly the same on ALL of the cache chips (9436 for the tag ram, 9431 for the bank 0 chips, 9412 for the bank 1 chips).

Is this board known to come with "half and half" fake cache? The chips marked "9412" look weird compared to the others, you can remove them and the board works exactly the same.
Even more interestingly, the manual mentions nothing about how to configure the cache jumpers - it mentions it can support various configurations, but it doesn't have anything about settings.

I also happen to have some spares - four 256k chips at 12ns that are known working (pulled from a different motherboard I upgraded ) along with their own tag ram chip. Tried swapping these out - the board doesn't even boot if I put them into Bank 1 (leaving the original H61256-20 on bank 0, not sure if this is expected due to the timing difference); It does some utterly weird crap if I install those, along with their tag ram chip, into bank 0 (leaving bank 1 empty). By "utterly weird crap" I mean the CPU performance in Speedsys fluctuates and sometimes it reports a "ghost" extra megabyte of video memory...

Hi
I had that same board as your and I can confirm that it was a NIGHTMARE to configure the Cache of that board
Even though it reported 256k in the boot screen, Cachecheck only detected 32k !!!

I played with the jumpers for HOURS and sometimes the board would freeze
then at some point I managed to make Cachecheck detect 128k

I also suspected some bad cache chips so I replaced all the bloody chips with proven working ones.
Then after fiddling with the jumpers again for another half hour it finally started working with 256k
The jumper settings on the retroweb picture didn't work for me to 256k

So I sold the bloody board (with the 256k active) and I have the original chips on a bag to test them at some later time.

I can confirm that the board came with 2 sets of different branded chips.

Good luck !

Nunoalex wrote on 2025-09-26, 15:32:

Hi I had that same board as your and I can confirm that it was a NIGHTMARE to configure the Cache of that board Even though it r […]
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Hi
I had that same board as your and I can confirm that it was a NIGHTMARE to configure the Cache of that board
Even though it reported 256k in the boot screen, Cachecheck only detected 32k !!!

I played with the jumpers for HOURS and sometimes the board would freeze
then at some point I managed to make Cachecheck detect 128k

I also suspected some bad cache chips so I replaced all the bloody chips with proven working ones.
Then after fiddling with the jumpers again for another half hour it finally started working with 256k
The jumper settings on the retroweb picture didn't work for me to 256k

So I sold the bloody board (with the 256k active) and I have the original chips on a bag to test them at some later time.

I can confirm that the board came with 2 sets of different branded chips.

Good luck !

Similar experience. I've got a bunch of 512kbx8 chip delivered, and I was unable to get the board to boot at all by installing 4 of them in bank 0 (256KB).
Tried everything with the jumpers.
Tried to replace the board's tag chip (the weirdly marked H61257-20) with a Windbond W24257AK, same thing.

Then, just for kicks, tried to use one of the GL chips (GLT7256M08) as tag...and boom, it now works. All the way up to 512K of cache, in one wanted - but I left 256KB installed. Uncached ram access still slow as heck, at least going from the tests, however.

This however kinda opens up another question - what's the difference between the chips marked 257 and those marked 256? If you pull up the spec sheets, they all seem to be 32x8 sram chips. I've found discussions here that concluded it's just different manufacturers using different part numbers, however the fact that both the original H61257 and the W24257AK chips didn't work, while the GL one marked 256 did, suggests there's some difference. Winbond also used to make chips marked W24256AK. I haven't been able to find any definitive info...if anyone had any idea, please share 😀