Pentium Pro Motherboard with CMOS issue. DTK PRM-0031I \ VOGONS

Pentium Pro Motherboard with CMOS issue. DTK PRM-0031I

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First post, by Darrylo

Posted on 2022-11-10, 08:15

Darrylo Offline

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Hi all

(Mini Intro for my 1st post)
I've been into my retro PC hardware for a while but have only given it some real attention in the last few months. current working systems consist of a socket 370 and a K6-2. There is a small growing number of working and not yest(hopefully) working parts.

I received this motherboard (DTK PRM-0031I) yesterday only and before powering up I checked the jumpers cleaned up the ram contacts and checked for any physical damage.
On power up I got a string of 9 Beeps indicating a CMOS checksum error. Afte removing and all but 2 ram sticks, changing video cards checking the bios chip is seated etc it started to POST.

What I then noticed is it would not store the bios settings as it kept reverting to disabling my ps2 mouse. I did however notice it did keep the time.
I have not done much further diagnostics but want to start with the following:
Find the CMOS chip and see if it has power from the battery.
Figure out what version of AMI flash to use to update the BIOS.

Is there anything else I should check?

Reply 1 of 10, by Darrylo

Posted on 2022-11-10, 15:10

Darrylo Offline

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Update: Traced the power all the way to pin 7 on the PC87306 chip and all looks good.
Then... double checked the cmos and noticed its only the 1 setting that does not stay as set. The PS2 Mouse Support

Suppose I could use a serial mouse, but thats really not ideal.
so is it a bios issue or a PS2 port issue?

Reply 2 of 10, by weedeewee

Posted on 2022-11-10, 16:18

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Silly idea... if you set the date to before y2k, does the ps2 mouse support setting still change ?

Right to repair is fundamental. You own it, you're allowed to fix it.
How To Ask Questions The Smart Way
Do not ask Why !
https://www.vogonswiki.com/index.php/Serial_port

Reply 3 of 10, by Darrylo

Posted on 2022-11-10, 16:40

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weedeewee wrote on 2022-11-10, 16:18:

Silly idea... if you set the date to before y2k, does the ps2 mouse support setting still change ?

I have rebooted with reset bios in 1995 a few times with no difference.

Reply 4 of 10, by Darrylo

Posted on 2022-11-11, 05:48

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So there is no progress. the next plan is to reflash the BIOS.

I have located 2 ROMS but I have no idea which version of the AMI tool to use?

On a good note, the board was sold with 128mb of ram but after cleaning up and reseating them its a full 200mb.

Reply 5 of 10, by luckybob

Posted on 2022-11-11, 05:54

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Bios chips have limited re-flash ability. Every time you save the bios settings brings the chip closer to failure. Some chips last 10's of 1000's of times. Some are much quicker to give up the ghost.

If it were my board, I would flash a replacement and try that.

It is a mistake to think you can solve any major problems just with potatoes.

Reply 6 of 10, by weedeewee

Posted on 2022-11-11, 06:43

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luckybob wrote on 2022-11-11, 05:54:

Bios chips have limited re-flash ability. Every time you save the bios settings brings the chip closer to failure. Some chips last 10's of 1000's of times. Some are much quicker to give up the ghost.

If it were my board, I would flash a replacement and try that.

The bios settings on old boards were stored in a piece of battery backed ram, not in any eeprom.

that said, even ram can fail.

Right to repair is fundamental. You own it, you're allowed to fix it.
How To Ask Questions The Smart Way
Do not ask Why !
https://www.vogonswiki.com/index.php/Serial_port

Reply 7 of 10, by Darrylo

Posted on 2022-11-13, 14:29

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I managed to flash the BIOS. Tried 2. one was official latest Winbios and other was modded.
Neither resolved the issue.

Starting to think there is a issue between the controller and ps/2 header.

Reply 8 of 10, by Darrylo

Posted on 2022-11-14, 18:28

Darrylo Offline

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Problem solved.

After managing to trace the Vcc and Data to the controller chip, then checking the header pin layout to the plug....
The pins are non standard!
"standard" This board
1 Data Vcc
2 Blank Blank
3 gnd Gnd
4Vcc Clk
5 Clk Data

Reply 9 of 10, by luckybob

Posted on 2022-11-14, 18:55

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Somehow, I'm less than surprised.

I will admit, checking the pinout is pretty low on my troubleshooting list.

It is a mistake to think you can solve any major problems just with potatoes.

Reply 10 of 10, by Darrylo

Posted on 2023-11-03, 20:12

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Not sure if I should start a new thread, I'm considering using this for an OS/2 build...

I have only ever once run it for a short while but I think this setup with Pentium Pro 20o, 200 mb ram would make a good workstation.

I'm open to other suggestions on a workstation type setup for this CPU. (maybe as a retro server ?)

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