Eep386 wrote on 2021-09-09, 17:26:

Sure thing, glad to help. It sounds like the foundation of a pretty rad DX2 system though, so I'd like to see it up and running […]
Show full quote

Sure thing, glad to help.
It sounds like the foundation of a pretty rad DX2 system though, so I'd like to see it up and running soon!

Those empty skinny DIP28 sockets lower center and right in the mobo shot are cache sockets, you'll want to find some 32Kx8 15ns SRAM chips to put in them.
The shorter empty DIP sockets just above the Cirrus 5428 controller are empty sockets for 256Kx4 DRAM chips. 70ns ought to be sufficient, 60ns will work too but be sure you're getting FPM DRAM, not EDO.

The empty rows of pins around the CPU also hint at potential compatibility with the Intel Pentium Overdrive POD-83 too. Good luck finding one at a semi-reasonable price on eBay these days though.

I have Installed the cache and VGA memory expansions now, cache seems to be working. But how can I confirm that the VGA memory is detected? Does it usually need some BIOS configuration changes?

You can try running Speedsys 4.78. Though it doesn't always properly detect VGA card memory, it does so about 75% of the time.

Eep386 wrote on 2021-10-08, 19:44:

You can try running Speedsys 4.78. Though it doesn't always properly detect VGA card memory, it does so about 75% of the time.

I'm just running it and its hows VESA memory : Unknown

This is what it shows.
At least the cache is showing up.

Eep386 wrote on 2021-10-08, 19:44:

You can try running Speedsys 4.78. Though it doesn't always properly detect VGA card memory, it does so about 75% of the time.

After noticing that one of the VGA memory chips leg was bent and carefully adjusted it to fit again in the socket. I get result from Speedsys that there is now 512 KB of videoram. Like it's ignoring the permanently installed videoram on the motherboard.

So the question is, does it really use now only the added video memory or it's not just showing up correctly?
for example there is no change in Windows 3.11 in the amount of resolution options or is it just maxed out in the Cirrus Logic side already.
SetRes in windows shows maximum 800x600x256 and 1024x768x16.

Also I have also learned that memory in the machine is working perfectly. Weird stuff that happened before is gone, reason for that was the L2 cache being on the board and not properly configured with the jumpers.

FDD is still acting up, not updating contents of the A: drive after switching disks in DOS.
This works fine when installing DOS, but after install it just show the contents of the first disk and after swapping it only shows contents of the first disk inserted, workaround is power cycling the machine.
Funny enough that FDD works great in Windows.
Could this be some kind of DOS driver issue, is that even possible?

DDO with ontrack was not working very well with the CF card, CF IDE drive adapter combo that I have. The slow reboot time was fixed when normally partitioning with FDISK and then installing DOS to that.
Boot time to DOS is now 10-15 seconds compared to 15-30 minutes with Ontrack.
But this limits the size of the drive 504 MB. This seems to be very common issue, even when the bios can configure drive up to 8 GB, it is not actually working as that.

Solution for the drive size issue could be using XTIDE universal BIOS, but it's not very clear to me how this process works?
I have 3COM networking card with empty BIOS socket, that could be used to flash the BIOS on some EEPROM?
What kind of EEPROM chip do I need?
How can I know that BIOS is compatible with the motherboard that I have?
How is the new flashed BIOS used by the system? Does it replace the BIOS on motherboard, does it work somehow side by side with it, how do you configure it?
Or is it only flashed in DOS and then motherboards BIOS is replaced with the newly flashed EEPROM?

So much questions!! 😀

Regarding the missing VGA memory, I'd check for a jumper setting that's amiss. Normally there aren't any but with systems that have integrated video, who knows.
Also, I've ordered what I thought were 256Kx4 DIPs and were even marked as such, but as it turns out they were really 64Kx4 DIPs. Wiping the surface of the chips with acetone strips the top markings and black layer off (no it didn't reveal what was underneath, they were pretty well ground off). Friggin eBay. 😜

It's also distantly possible that there is indeed 1MB installed yet the video BIOS is limiting it to 512K only, but this is slightly unlikely if it's using a 'vanilla' Cirrus BIOS.

Updated the OP to reflect what has happened so far.