I will try to explain the problem as best as I can, as I don't speak/write English fluently, so I apologize for that.

After uploading some photos, manual and bios file in this thread:
Re: The Retro Web submissions thread: suggest edits and/or add new boards here
of this motherboard (Rectron RT-4S3), i took the opportunity to do some tests since I had the motherboard in my hands.

I run speedsys 4.78, and verified that it did not detect any second level cache.On the bios the external cache was enabled.
So i removed all 4 cache and TAG chips and tested on the TL866 and the Retro Chip Tester giving them as damaged.

Cut one chip in half and...no silicon chip !...

So like PCChips this motherboard had fake cache..., i thought only PCChips had fake cache on their motherboards...

But I also found another problem, see the photos of the TAG RAM socket, the VCC pin (+5V) is missing, so the (ghost) chip has never been powered...

Since the motherboard no longer had a true cache, they didn't even notice the problem.

Regarding the bios, without cache chips, the boot screen always reports 256k of cache, but with real cache the indication
is the correct, i tested with 128k and 512k of total cache.

So, i think this bios can be used without any problem with good cache...