strong board

486 CPUs are using 32bit external data bus, thus only one 32bit SIMM72 stick is needed for such system to successfully POST, wherereas socket 4/5/7+ CPUs are using 64bit external data bus and thus require at least two simm72 sticks 😉 There exists at least one S7 chipset that can interface a 64bit external bus CPU with a single SIMM72 stick with a performance penalty, but generally CPU data bus width should be equal to RAM data bus width per bank.

SSTV2 wrote on 2021-02-20, 05:27:

486 CPUs are using 32bit external data bus, thus only one 32bit SIMM72 stick is needed for such system to successfully POST, wherereas socket 4/5/7+ CPUs are using 64bit external data bus and thus require at least two simm72 sticks 😉 There exists at least one S7 chipset that can interface a 64bit external bus CPU with a single SIMM72 stick with a performance penalty, but generally CPU data bus width should be equal to RAM data bus width per bank.

Yes, but this motherboard is kind of strange in that sense, all the valid memory combinations in the manual use either 2 or 4 banks/slots. Maybe some chipset limitation?

Other than that, it is a very fast board, ideal for a 5x86 or POD83.

Interesting, it uses a UMC 888x chipset, which definitely can work with a single SIMM72 stick, I wonder if such two-sticks-per-bank configuration significantly increases memory throughput on that chipset.

The board works fine with only one memory stick - I have three different versions of this board and all work fine.

There is no difference in memory throughput when used in pairs.

Well, I got it sorted (somewhat). The DX2-66 CPU has a bent pin and after inserting my 5x86-P75 3.3V CPU in the socket, it boots up and goes through the memory count.

The other issue is the RTC Dallas chip that has the battery holder to swap out the batteries easily doesn't retain the settings, even though I inserted the chip the right way. I don't see any jumper settings that controls the normal/clear settings. The time is correct, but the date is off by 27 years.