I recently bought this kind of common unbranded 368Sx33 ALI M1217 motherboard. It came with 4 256kb 30 pin RAM modules.

As you expect from motherboards of era, the leaky battery was removed. When I fired it up, it counted memory to 1024 but the last few hundred KBs it skipped through with the fast ticking sound, then complained about bad CMOS. When I set the CMOS and reboot, it counts memory only up to 768KB.

I tried to find any of hardware issues; switched SIMMS around and replace them with the two extra 256kb that I have, also checked signals and traces, all seem to be fine.

Right now, I do not have any other capacity SIMMs to check if total memory goes higher 1 MB.

I kind of remember some other systems skipping the upper memory too but still not sure if this is normal for this computer.

I also used CheckIt before and after CMOS set; images attached. The part I find puzzling that after CMOS set, CheckIt reports 640KB conventional, 384 reserved upper memory and 128 KB extended, is 128 extended part of that 384 upper memory?
CheckIt run before CMOS set, reports a negative (!) extended memory and skips extended memory test.

If you know the explanation for this behavior; please share it with me as I have minimal knowledge of dos and 386 memory mapping.