I have a few Suntac 286 boards coming from several 286 computers I bought as a job lot. (Details on the systems are here.)

I have two working boards so far, the other ones need repair. Here is the first one with 2MB RAM.

The second one with 4MB RAM (It also came with 2MB but I added the RAM chips from a non-working board to make a total of 4MB)

BIOS on both boards is Phoenix 3.10.22:

Thanks 😉 I think your BIOS is the most up to date so far 😉 Can you add an image please? You can extract it with NSSI or also debug.exe, let me know if you need instructions.

I'm not so familiar with the process of making images but I have NSSI, so I'll try to figure it out next time I have access to the system and post my results here.

I've finally managed to make an image of the Bios from the above board (Phoenix 3.10.22):

MMaximus wrote:

I've finally managed to make an image of the Bios from the above board (Phoenix 3.10.22):

phoenix.zip

Thanks for the upload again! I have splitted your image in the HO/LI portions and tested in my board. It powers up, but I am not able to enter Setup. Every time I press F2 it reboots...

I assume the image is not complete and the file needs to be 128kb in size. Its similar to the AMI Diagnostic ROM I posted above. This one powers up with the 64kb part only, but you are not able to enter the diagnostic menu.

Therefore: Can you please try to dump the ROM area from E000:0000 to F000:FFFF? This should give a 128kb file.

Thanks!

If you tell me how to proceed I can certainly try! But please note that on this board I haven't been able to find a way to enter setup. The only way seems to be changing the configuration e.g. removing one floppy drive - then there will be a prompt saying "press F2 to enter setup".

MMaximus wrote:

But please note that on this board I haven't been able to find a way to enter setup. The only way seems to be changing the configuration e.g. removing one floppy drive - then there will be a prompt saying "press F2 to enter setup".

Same here on mine. I have to do the same thing. I've tried Ctrl-Alt-Esc and a bunch of other common key combos.

MMaximus wrote:

If you tell me how to proceed I can certainly try! But please note that on this board I haven't been able to find a way to enter setup. The only way seems to be changing the configuration e.g. removing one floppy drive - then there will be a prompt saying "press F2 to enter setup".

OK, with NSSI you can try "Save ROM modules" and see which files are generated.

Or use debug.exe. Type:

debug e000.rom
rcx
ffff
w e000:0
q

And post the file e000.rom. This file will be also 64k, but I will combine with the one you already provided.

Ups..had an idea where the mistake is. Had to switch the jumper on the Mainboard from 27128 to 27256. Now it reads the whole chip and I can enter Setup:

No BIOS at E000...

Also attach the Hi/Lo files of your image for programming.

Thanks again!

liqmat wrote:

MMaximus wrote:

But please note that on this board I haven't been able to find a way to enter setup. The only way seems to be changing the configuration e.g. removing one floppy drive - then there will be a prompt saying "press F2 to enter setup".

Same here on mine. I have to do the same thing. I've tried Ctrl-Alt-Esc and a bunch of other common key combos.

Crtl-Alt-Esc works 😉

Wait until all 3 Keyboard LEDs flashed simultaneous after Video card initialization. Then press Ctrl-Alt and keep it pressed. Then continiously hit the ESC-key (maybe 2x per second). Then the "...F2 for Setup.." message appears.

Beautiful collection. Thanks for sharing.
I have one Suntac based mobo as well. Still works like charm. I don't quite remember how I got it, but it was many years ago. In fact it's my only working 286 mobo right now, because it seems I have bad luck buying them - last one I bought had minor battery leak dammage which I thought I fixed only to watch a small firework show when I turned on the power, another one I describe in another topic here, third one is lost in the shipping 🙁 and fourth still didn't arrived. I'm ordering these things like crazy for the same reason you did (I learned most things I know on a machine like this).

Here is my Suntac-286P motherboard: https://i.imgur.com/pgORBr7.jpg

One of the early boards to incorporate HDD and FDD controller. Also all chips (but CPU and chipset) are socket mounted which is a good thing.

Predator99 wrote:

Ups..had an idea where the mistake is. Had to switch the jumper on the Mainboard from 27128 to 27256. Now it reads the whole chi […]
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Ups..had an idea where the mistake is. Had to switch the jumper on the Mainboard from 27128 to 27256. Now it reads the whole chip and I can enter Setup:

DSC_7790.JPG

No BIOS at E000...

Also attach the Hi/Lo files of your image for programming.

Phoenix 3.10.22 NSSI.zip

Thanks again!

Sorry I'm not sure I understand your post - does this mean the previous image is working? Or do you still need me to do the debug thing?

No everything OK and working! 😀

Predator99 wrote:

No everything OK and working! 😀

OK good to know 😀

First a big thanks to MMaximus to send me this very nice (but not working) Suntac board!!! 😀

It is labeled "AMA-1240V1-D".

Bios is the Phoenix 3.10.22 as posted above.

As the board was not booting, I first tried the Supersoft ROMs. I tried 3 different CGAs, but no display. Beep codes are:

6-1 Cannot initialize monitor
6-2 ?
...
6-1 Cannot initialize monitor
3-3 CMOS RAM
...
3-4 Floppy adapter

Everything seems to be OK, except the Monitor...! Had no success in removing all socketed ICs or playing with the Jumpers. Also tried other RAMs.

Then I tried again with the original Phoenix BIOS. Post sequence is:

00
01
02
03
04
05
06
08
09
0d
20
21
22
23
25
27
28
29
2c
2b (Screen memory test failure) / Beep: long short long short
2e
34
35
00
3A
38 (Memory high address line failure at 01000-0A000 (non-fatal) / Beep: short short
00

This indicates an error accessing/adressing the Video memory? Tried several VGAs, same result. To my surprise, the board is up after finishing the POST. I can switch the keyboard LEDs and a reboot with Ctrl-Alt-Del works.

No idea at the moment, no damage visible except some minor battery corrosion. All LEDs on the POST card are OK.

Will continue trying, but any idea is welcome 😉

Did not manage to fix it so far...

But next one:

After some cleaning it looks better:

Seems to be alive, but the delay line in the bottom left is loose, almost all pins broken. Need a replacement...

BIOS:

That poor thing… look at the corrosion on the ISA slots!

Predator99 wrote:

This indicates an error accessing/adressing the Video memory? Tried several VGAs, same result. To my surprise, the board is up after finishing the POST. I can switch the keyboard LEDs and a reboot with Ctrl-Alt-Del works.

My guess would be a problem with one of the address lines on the ISA bus. The way these mobos are wired it's very unlikely to be a low byte data line issue since that would upset the big chips with DMA controllers and whatnot. And the lower address bits seem to work OK-ish for the same reason but it could be a line being stuck for example.

First, test the video card in an 8-bit slot if you haven't already. This board seems to have two, and conveniently almost at the opposide sides so try both. If that doesn't work then it's going to be more work for you. Get a meter with good, fast beep on short and check all the address lines on the upper 8-bit slot. Here's a pinout: https://en.wikipedia.org/wiki/File:XT_Bus_pins.svg

It's easy, just one side to test, and not even all of it. For each address line check:
- that is not shorted to ground
- that is not shorted to +5V
- that is not shorted to any other address lines
- that there is connection to one of the pins of ST62BC004

Now, the exact pin on '004 doesn't matter as long as there is a connection somewhere. Take your time with it, you don't want to miss any of these tests. Also, inspect all of the slots and make sure there isn't a bent contact anywhere that would short the ISA A and B sides - that can be verified with the meter as well but a good look should suffice.

Like to give an intermediate feedback...cannot continue with beep-testing as somebeody else here is annoyed 😉

I tested again a CGA and VGA in different slots - same results.

So I tested all Pins in the 8-bit ISA Slot 1 against Slot 8 - all connected.

But there is no conection of all adress lines to the ST62BC004. But no surprise: I followed some traces and some go the area around the CPU. So there cant be a direct connection to the ST62BC004...

EDIT: OK, tracked the adress lines as far as possible. Some end in the ST62BC002 the remaining in the St62BC003.
From a optical point of view all perfect, but will verify.

Predator99 wrote:

But there is no conection of all adress lines to the ST62BC004.

Oops, sorry about that. I looked at the wrong bus and gave you data lines to check. So, actually it's like this:

Addresses A1-A12 go to 003 chip, and A13-A19 to 002. I haven't yet found which chip decodes A0.
For now though check the A13-A19 lines first, and then move to /MEMR (B12) and /MEMW (B11) which should be connected to 001, most likely through 30 ohm resistors. Let's get this out of the way first.