No, the USB drive cannot read any disk. I tried two known good diskettes and it ended up leaving a big gouge mark in one of them on it's second attempt - Cleaned the drive and it didn't gouge a third disk, but it still wouldn't read. The drive is probably physically damaged, it's fairly old and I got it for free anyways. I've been long overdue for a new one. Know anywhere I can get a NOS Teac USB floppy drive?

I don't have XTIDE, I'm using a DTC 7287 RLL controller with it's own BIOS. The motherboard's own Award BIOS and the DTC support high density diskette drives by default.

Again, I'd try these things, but I can't get anything on the machine right now. All I can do is move things between the 286 and my Compudyne 3SL/25, the only other working machine with a diskette drive right now. It's a fairly basic 386SX laptop from the late 80s, it doesn't have an optical drive or PCMCIA or anything I could use to transfer files to it besides a diskette drive and a serial port as well. I couldn't get FastLynx to work with it either.

Scouring around the depths of the internet and old PC Magazine and InfoWorld editions, I've discovered that this machine also went by another name:
"Vector Excalibur 286"
The case is not the same, but the motherboard uses the same chipset and CPU. It also shipped with a similar configuration. Several articles even list it shipping with the exact same 1.2MB Teac diskette drive.

An article in PC Magazine shows that it has a switch to change between 8 and 10MHz ISA bus speeds, something my machine can do, and supports 1 megabit RAM chips. "From 512K to 4MB"

It could also be a "Zeos 286/20," since it has a very similar case, the same NEAT chipset, the same 20MHz 286 CPU, and theirs shipped with 4MB of 1mbit DRAMs. Apparently it could be ordered with an MDA card, the same 1.2MB Teac diskette drive, and a Seagate hard disk. It also has an LED "CPU speedometer" on the front.

"DATA-286" is shown to have an exactly identical case and similar specifications. Not much else is talked about the machine.

Also, I've got a new USB floppy drive coming in tomorrow so I can finally get back to working on my machine!

Finally, my USB drive came in the mail... 6 days late. I've got CheckIt 3 and INFOSPOT on a diskette to try in the 286 now. Anything else I should stick on a disk to transfer over for tests?

Well, CheckIt can't seem to find anything wrong at all. Every test passes, excluding the random write for diskettes and things requiring loopback cables, which I skipped.

I don't see anything out of the ordinary anywhere on there. I can post pictures if need be.

It's a Chips NEAT chipset for sure, I pulled the motherboard out and had a look at it. Here's a picture of that:

Alright, so I replaced the battery outright. As it turns out, under any load it drops to about 2 volts. Figured this might be a problem, so I put a 4.5 volt battery pack and set the jumper to be correct.

The clock is no longer off by any amount, but I still cannot get anything out of the extended setup.

Changing ANYTHING in the extended CMOS page or simply changing it form disabled to enabled will cause the machine to hang when I restart. When Power cycled, the information is back to what it was.

Any thoughts?

By some random chance, I managed to get the onboard memory working! I don't even know what I did, but at some point it just... Detected more memory than usual.

Now, it's by no means working perfectly. There are 2MB onboard, but it's only recognizing 1664K of that. 640K conventional and 1024K extended - I'm pretty sure this is because it's skipping the 384K reserved. Fair enough.

When installing the AST Advantage, however, if I put it's starting address at 1664K, it's 384K short of what it's supposed to be. This suggests a conflict.
Putting it at 1920K, I'm 128K short of the installled memory. Good, I'm getting closer.
Putting it at 2048K... I'm 1152K short of installed memory. It's not even seeing the AST card at this point.

So best case scenario, I'm missing 384K of my system board's memory (probably reserved and might be being mapped to UMBs), and I'm missing 128K from my AST Advantage. This is an entire bank of the AST's memory, which was working before the system board memory decided to come back to life.

Thoughts on this phenomena?

EDIT: The computer booted just fine, then when HIMEM.SYS loaded, I got an "Unreliable memory" error. Rebooting the machine, I got the following message:

1MEMORY VERIFY ERROR AT 1:8000:0000 FOUND AA55 EXPECTED AA55

This is happening at every boot now. It... Finds what it's expecting.

Removing the AST board brings it back to normal.
Any help?