Tested with RAM removed (128 kB system), got same error.
Swapped in new BIOS ROM chips, error persists.

Tried two different NEC V-20 D70108C-8 CPUs, would not boot with either. They worked on my PCjr (4.77 MHz), and should be rated for 8 MHz, so I'm not sure why they didn't work. Got them many years ago but I suppose it's possible they are relabeled and are really the slower speed model. I did check the CLK (CPU pin 19) and looked like a good 8MHz signal to me...

The other diagnostic tests all seem to pass just fine. I wish I knew what the 100 test was testing exactly where it detected a failure.

Without a service manual the best way would probably be to look at a PS/2 model 30 emulator or run the starter disk in such an emulator, and in quickly looking, there isn't one.
The starter disk has the utilities spread across a bunch of files, so it'd be a bit annoying to try and study it off-line.

last year i went through 2-3 of these boards - fragile ballerinas.

some info in the link below helped me. take a look. search for 101.
https://www.minuszerodegrees.net/5160/post/51 … 0set%20to%20EGA.

edit: if you need spare parts let me know.

jakethompson1 wrote on 2025-04-01, 01:26:

Without a service manual the best way would probably be to look at a PS/2 model 30 emulator or run the starter disk in such an emulator, and in quickly looking, there isn't one.
The starter disk has the utilities spread across a bunch of files, so it'd be a bit annoying to try and study it off-line.

I went through the "PS/2 Hardware Maintenance Manual" Generic Checkout (AT Bus), but it basically just says to run the advanced test and if it gives an error, replace the indicated part...in this case the motherboard 😁.

It appears that error 1XX indicates system board. And may line up with the "0001 01XX" error listed on the Ardent Tool of Capitalism website here https://www.ardent-tool.com/trouble/error_01.html.
Symptom / Error:
0001 01XX
Interrupt failure.
Possibly a bad battery or processor

FRU / Action:
1. Run Advanced Diagnostics
2. 486DX33 Upgrade (70/80) (N/A here)

So possibly an interrupt failure? Battery for the RTC was replaced and the time/date seems to be working just fine, so if that error code matches up it would suggest an interrupt or processor issue?

Yeah, I thought about trying to find out which exact program was running and decompiling it....but that would take a lot of time 😁, and I'm not that quick with assembly.

pshipkov wrote on 2025-04-01, 01:41:

last year i went through 2-3 of these boards - fragile ballerinas.

some info in the link below helped me. take a look. search for 101.
https://www.minuszerodegrees.net/5160/post/51 … 0set%20to%20EGA.

Hmmm...so yeah, that list some possible options, although it's interesting that I don't get the errors at POST, only when I explicitly hit them with the diagnostic disk tests.

101 displayed on-screen […]
Show full quote

101 displayed on-screen

Some possible 101 causes:
• Motherboard's 8259 interrupt controller chip (includes supporting chips).
• Motherboard's 8253 timer chip (includes supporting chips).
• Motherboard's 8237 DMA controller chip (includes supporting chips).

NOTE: For detail, see actions '8259 TEST' and 'TEST/SET TIMER 0' and 'DMA TC0' at here.

Honestly I have yet to see it actually not work correctly...other than the odd mis-identifying 384 kB on first cold boot. Guessing cold solder joint on that one. Of course a DMA error might fall back to non DMA mode if that were the issue? Not sure.

Did you have any luck fixing any of your boards?

the initial ram count being off is telling.
either the onboard mem, or the simms, or a bad connection.

if you decide to change the onboard memory - be careful. these boards are sensitive there.

i had 2 of my boards alive and well. then decided to "upgrade" the onboard memory and that was the end of them.

the third board came doa. was able to resurrect it to a beeping state during power on, but never got picture on screen.

pshipkov wrote on 2025-04-01, 02:08:

the initial ram count being off is telling. either the onboard mem, or the simms, or a bad connection. […]
Show full quote

the initial ram count being off is telling.
either the onboard mem, or the simms, or a bad connection.

if you decide to change the onboard memory - be careful. these boards are sensitive there.

i had 2 of my boards alive and well. then decided to "upgrade" the onboard memory and that was the end of them.

the third board came doa. was able to resurrect it to a beeping state during power on, but never got picture on screen.

Without any added ram chips, it counts to 128 kB on POST every time. Although the advanced diagnostics likes to report it at something odd like 359 kB (I forget the exact number without looking over my notes, but it's not 3 x 128 kB even, it's weird).

With the added 2 x 256 kB SIMMs, it reports 384kB on a cold boot and 640kB shortly after. Doesn't seem to matter which SIMM is in which slot. So.....suspecting a cold solder joint on one of the lines to the SIMM somewhere.

And I figured out why the D70108C-8 didn't work....I forgot I was dealing with an 8086 and not an 8088 *smh*, so that explains that at least. The D70108C is a 8MHz rated 8088, not 8086.

I'm going to do an inspection of traces, connections and see if I can find a cold solder joint for the memory and maybe look around the 8259, 8353, and 8237 chips if I can find them for anything suspicious.

Still not much progress on this. Socketed the 82535 and 8237 chips and swapped with a different set of chips and no change. Was a bit of a long shot but was worth trying.

I have a second board now that passes all tests so at least I may be able to compare them at some point to try to isolate better.