I have the U3911-V3, but its not running as far as I remember. What do you like to know?

I have a option to buying it: I would like to know "jumpers settings". Do you have the manual?

Thanks in advanced

Hmm, no. I dont think you need it. There are not that many Jumpers. Speaker, Reset, Turbo, several LEDs and the DIP for memory configuration I assume. Trial+Error 😉

Predator99 wrote:

Trial+Error 😉

This is plan B 🤣 . My first option or plan A: I prefer get the information without trial+error

Have a look here (under 286 motherboards): http://arvutimuuseum.ee/th99/#1

You might find a motherboard with a similar layout.

Yes. I looked at there. No luck!!

I looked for this another board (Super 286-Z) too there:

No luck!!

Dont worry, you will get this running without documentation...

Does the seller say the boards are working?

I would prefer the Chips. But the memory does not look complete here. Dont think its working that way. But if yes, you only have 256 kb there.

Hi Predator99!!

Predator99 wrote:

Dont worry, you will get this running without documentation...

Does the seller say the boards are working?

No. He said to me: the mobos were working when they were uninstalled a long time ago. I previously bought two 486 mobos in the same conditions and they are working properly. The prices are vey low.

Predator99 wrote:

I would prefer the Chips. But the memory does not look complete here. Dont think its working that way. But if yes, you only have 256 kb there.

I don't understand. I do apologize. My english is very poor. You prefer this motherboard. Is it right?

In that board, what kind the memory chips are? There is only 256KB? Can I upgrade to 1 MB? What type of memory IC do I need for memory upgrading? (I'm so sorry for doing a lot of questions)

Thanks in advanced

I think the seond board with the CHIPS P82C chipset is the nicer one. But it seems only to have 256kb of Memory.

The VLSI Board: I think its 2 MB. The RAMs installed on this board are rather expensive (21010? / 411000?).

You should buy both 😉 You can exchange the RAMs between the boards, but only certain combinations are possible.

Here are the Jumper Settings for U3911-V4 (sry, not V1):

J2 - next to battery - Reset
J9 - Turbo LED (1:+)
J8 - Power/Keylock (1:+,3:gnd,4+5:kblock)
J5 - Turbo-SW
J7 - PCSPK (1:+,4:-)

I don't know anything about the dip switches but I think they help the bios to determine the graphics mode and can be fiddled with. My computer was equipped with oak vga adapter and a MDA adapter. There are only 16 Combinations, mine was set to 1:on 2:on 3:off 4:off.

I hope this helps.

Now my Problem:
At the moment my Boards is broken. Last week it worked, now it makes a post-beep code and no picture. no keyboard-leds. 2x Long, 3x short beeps. Google says:
Low 1-1-3 Extended CMOS RAM failure The extended portion of the CMOS RAM has failed. Replace the CMOS if possible

I have replaced the CMOS which is a HM6818A, with no luck.

Best regards,
phonox

Hi everybody,

great news. I had it socketed wrong! . After cleaning and reseating it, the replacement CMOS totally did the job!!

If you need anything about this board, answer to this thread. I will do what i can!

I am sooo happy now. As everything is original. And this is what it looks like:

phonox

Hi again,

after reinstalling the CGA card and a parallel port card that had been installed before, the symptoms came back. Reseating the cmos doesn't help.

What could be the reason for this failure? The CGA-Card in Slot 8? (without monitor, it was useless anyway) The CGA Card was installed in the only 8-bit slot at the lower end of the mainboard. Or maybe the parallel port card caused some nasty electrical issues on adr/data bus? Removing the components doesn't help.

I think, the new cmos is also broken now.

I will not put any suspicious cards into the machine anymore. And order a new old stock cmos.

best regards,
phonox