"JUKO" on the sticker is a lead - JUKO was seen quite a lot in those days.

Good news: I think I've found the PCB:
https://theretroweb.com/motherboards/s/juko-b0007

Bad news:
- it's being used for a 386SX there, not a 286 (quite common in the early 1990s, very late for 286)
- no jumper manual or other info

WSO and WS1 probably select the wait states rather than doing it in the BIOS.
ROMWS is probably ROM wait states, since reads from the ROM might need a wait state for some reason (slower ROM chip I suppose).
16 BIT ROM EN is probably "16-bit ROM enabled".

I don't see any 1/1, 1/3 markings on that picture despite zooming so I have no idea on that one. Could be ratios of the FPU to CPU, but often the FPU would run at 2/3rd the CPU speed.

dionb wrote on 2024-09-09, 21:31:

Bad news:
- it's being used for a 386SX there, not a 286 (quite common in the early 1990s, very late for 286)
- no jumper manual or other info

Oh, thanks, I wolk to TRW and looked at different 286 motherboards, hoping to see familiar letters, but did not look at 386. I guess now I need to try to find a 386 motherboard with similar jumpers and dips

AlaricD wrote on 2024-09-09, 21:38:

WSO and WS1 probably select the wait states rather than doing it in the BIOS.

Thank you. That makes more sense. I was thinking about it, but why two? One would have been enough. 1/1 is jp2, I'll check when I get home

With all those jumpers and dip switches, I'm guessing there's not much left to configure in the BIOS program. Does it boot at all? Can you probe clocks to see if the CPU frequency is correct?

wbahnassi wrote on 2024-09-10, 13:46:

With all those jumpers and dip switches, I'm guessing there's not much left to configure in the BIOS program. Does it boot at all? Can you probe clocks to see if the CPU frequency is correct?

Hello. I have two identical motherboards. This one has a broken power connector and one memory chip is missing. The second one survived and starts up, but it does so very slowly even in turbo mode, I don't like it, but it works fine in games. The BIOS looks regular. The jumpers on the second motherboard were missing and I matched their positions with this one, but the dip switches are set differently. I took these boards from a very bad place for computer, and I am almost sure that the settings are set randomly. I also took two cases from these motherboards, on the front panels there are frequency indicators: non-turbo - 12 MHz, turbo - 16 MHz, which does not look true. The crystal oscillator is set to 24, the processor marking is 12. I am confused. What program should I use to know the real processor frequency?

Calombuti wrote on 2024-09-10, 09:46:

Thank you. That makes more sense. I was thinking about it, but why two? One would have been enough. 1/1 is jp2, I'll check when I get home

Often, a jumper block like that means that depending on whether positions 3-2 or 2-1 are closed, a different result occurs. Could be 2-1 for "normal operation" and 2-3 for "clear CMOS" or any number of things. It may refer to whether the NPU uses an internal or external clock, which can matter depending on what NPU is being used.

12MHz is an expected speed of a 286. A 24MHz crystal is also the correct one to tick the guy. The 286 needs two clock ticks, hence 12x2MHz. Not sure about 16MHz. But if there is no 32MHz crystal on the board, then 16MHz won't be achievable. It would be 12MHz on Turbo, and less than that (probably 4MHz) on deturbo. Make sure you jumper the turbo switch to run the CPU at 12MHz, otherwise it will run at XT speed.

AlaricD wrote on 2024-09-09, 21:38:

I don't see any 1/1, 1/3 markings on that picture despite zooming so I have no idea on that one. Could be ratios of the FPU to CPU, but often the FPU would run at 2/3rd the CPU speed.

If this applies to the FPU, then it's strange.

Calombuti wrote on 2024-09-11, 12:27:

AlaricD wrote on 2024-09-09, 21:38:

Could be ratios of the FPU to CPU, but often the FPU would run at 2/3rd the CPU speed.

If this applies to the FPU, then it's strange.

That unpopulated DIP40 socket is almost certainly for the 80287. The jumper block is quite close to it. You might also notice that on the 386 variant of your board referenced above, the 68-pin Leadless Chip Carrier (LCC) is right up in about the same spot as the DIP40 is on the 286 board.

Yes it is, but I would expect to see 2/3 there, as you wrote earlier about the same thing. As far as I know, 287 had a minimum of 6 MHz, 286 from Intel - a maximum of 12 MHz. So the 1/3 jumper is doesn't make sense unless you are installing faster processors from AMD, Harris or Intersil. The best version is 1/1 - synchronous mode, 1/3 - asynchronous mode for 287, and the 1/3 designation was reserved for the future, for 386 and 387. In fact, now I think most of the jumpers and dips on this board will not work for 286. I have an old 286 that has 5 jumpers on the motherboard - parity error chek, memory type, wait state, color and external battery. Now I plan to practically check with software what each jumper and dip does.

Dump BIOS if you can, it must have unique POST string(AMI), if board is know, you get hint

Calombuti wrote on 2024-09-11, 12:27:

AlaricD wrote on 2024-09-09, 21:38:

I don't see any 1/1, 1/3 markings on that picture despite zooming so I have no idea on that one. Could be ratios of the FPU to CPU, but often the FPU would run at 2/3rd the CPU speed.

If this applies to the FPU, then it's strange.

Yes and took me a few to dust cob-webs from my old brain. If it applies to the FPU: could be for Sync versus Async but with 24mhz xtal and 12mhz cpu seems it be same 8Mhz fpu speed either way unless my math is wrong :0

Mov AX, 0xDEAD wrote on 2024-09-11, 22:49:

Dump BIOS if you can, it must have unique POST string(AMI), if board is know, you get hint

Hello, I have no way to make a dump. I need the board identification to try to find a description of the jumpers and dip switches