I think it's more likely to be the P54CE: https://theretroweb.com/motherboards/s/lucky- … rev-f#downloads

COAST modules are not guaranteed to be interchangeable, so you may need to check where Ground and Power are. There was a thread here with a couple of pinouts: Pentium COAST / CELP L2 cache sticks standards

Thanks snufkin.

I believe I'm on top of the Ps2 port pinout - I checked virtually every socket 7 lucky star motherboard doco i could find and they all have the same pinout. Gonna trust that its the same again for this.

Where´s the "fake cache" supposed to be?

I see two Galvantech SRAMS -> real cache.
two Intel transceivers/ buffers -> have nothing to do with cache
and a COAST slot -2nd half of 512K real cache except when you would insert a fake COAST module. I have never seen such a module.

the 3rd image attached - there's no markings on the top chips above the COAST slot. just black plastic. thats what i was concerned about. if those are not related to cache then I am happy that its not an issue 😀 thanks

foil_fresh wrote on 2022-12-10, 13:52:

I believe I'm on top of the Ps2 port pinout - I checked virtually every socket 7 lucky star motherboard doco i could find and they all have the same pinout. Gonna trust that its the same again for this.

You should be able to ID which pins are +5 and GND with the board off by measuring resistance to ground and +5 on either the keyboard or power connector. That just leaves clock and data, so worst case is just try one and if it doesn't work swap them round. That said, it's likely they'll have reused the same pinout.

[edit to add: I think those two chips are part of the Intel chipset, 82438VX. Can see the faint Intel 'i']

[curious, comparing the photo of your board with one of the ones on RetroWeb, and they're bother marked P54CE, but the jumpers between the CPU and cache are different. In particular, yours doesn't seem to have any jumpers for setting the cache size.

Also, I've had a go at a translation (or rather, Google had a go) of that Russian sheet on the VX1:

But, no information about JP1, CN2 (I assume the PS/2 header) or JP15 (clear CMOS maybe?)

[last edit... Looks like yours has more options for bus speed compared the other one