BitWrangler wrote on 2021-12-01, 19:11:

Uh oh, PS/2 modules have the presence detect jumpers set different to standard.

Problem? Is it the chips themselves or the modules? Something I can deal with soldering (the jumpers) ?

Basically all SIMMs for sale states "PS/2".

8MB Ps/2 Fpm 72-Pin Simm Mémoire Double Face PC Memory 60ns 5V TMS44400DJ-60

https://www.ebay.com/itm/284521705268

Ah panic too soon, you're okay with 8MB it's one of the sizes they agree on... https://eprm.ardent-tool.com/eprma/h871.htm

Anonymous Coward wrote on 2021-12-01, 18:34:

TMC/Mycomp

I've got a dual socket 8 board from them that's been a huge headache, was everything they made just bargain bin shit?

I will try to use this to derive the vendor behind it:

http://lmg-data.dk/Pc/award.htm

I know it is using Award BIOS.

BitWrangler wrote on 2021-12-01, 19:27:

Ah panic too soon, you're okay with 8MB it's one of the sizes they agree on... https://eprm.ardent-tool.com/eprma/h871.htm

Thanks for the link, I never really understood the discrepancies between IBM PS/2 compatible modules vs what sane people building AT compatible machines really needed.

But I do recall that you had to stay away from say Compaq and IBM modules 🤣

So it all boiled down to wiring the last pins to GND to help the chipset identify the specs accordingly? Like a crude SPD rom then...

snufkin wrote on 2021-12-01, 19:05:

Something just occurred to me about those PI5Cs. Those diodes next to each of them might control power to the Vcc pin. That way they don't have to route to both !BEA and !BEB, and just turn the power on or off. Drive pin 2 of the diode high to connect the bus, or let it float/drive it low and Vcc get pulled low through the 4.7k resistor (I'm assuming they go to Ground), disconnecting the bus. It's a bit rough, and can't think why they'd need a diode for that. Stop the bus switches switching off too quickly?

Might be worth checking what those diodes connect to, maybe a jumper?

Ok I have doing some more probing. As you say the 4.7k resistor goes straight to ground effectively pulling it low. What is puzzling though is that the diode is connected straight to Vcc and I have been trying all kinds of jumpers, but no change. Same goes for !BEA and !BEB, no jumper changes the fact they go straight to ground.

I have also been fiddling with JP5, which alters the base resistance for the TIP127 PNP transistor. The 41DR to my understanding is a solid state relay?

Edit: 41DR was falsely identified as SSR when I Googled contemporary components. It is part of the PNP voltage regulator circuit, serving as the "voltage detector". The circuit closely resemble this one: https://powersupply33.com/positive-regulator- … -boost.html/amp

Possibly JP5 can change the output voltage for TIP127 somewhat (e.g., 3.3V vs 3.5V).

I did find the CLK source to Socket 4 as well and it goes via the same Bus Transceiver as the other clocks (except the CLK for Socket 5).

It is clear that the signaling from the chipsets are primarily wired to Socket 4, then splits and goes to Socket 5 as well via the PI5Cs.

Oh well, now I just need to get some components in and start testing 😅

Finally an update to this topic!

I did my homework and replaced the Varta 3 battery with a somewhat more modern NiMH counterpart. In fact the old NiCd happily charged up to 3.6V on my hobby charger 😀

Also had to resolder the ceramic decoupling capacitors sitting underneath the CPU package since those where pushing against the CPU itself. Most likely this was a tight fit with the early Gold heatspreader P90 CPU and the somewhat later revision P100 I have in possession protrudes just a tiny bit more.

Now on to my POST issues ->

With no memory installed or in the wrong memory bank/order I get PC speaker beeps with POST code:

C1BE (which indicates something about memory so fair enough)

With SIMM installed (in the assumed correct bank/order) - I tried several combos with the SIMMs I have - I get no beeps but the POST code:

060A (06 is Award BIOS reserved)

Edit: This is 0B 0A (as concluded further down in this thread) 😊

I have been searching for the 060A (0B 0A) POST code but to no avail. Anyone else out there who have observed this 🤔

ROM checksum error maybe?
http://www.bioscentral.com/postcodes/awardbios.htm

It is definitely not a PNP BIOS, it reads the following:

ISA/PCI 586
S/N: 013870745

Any feedback is much appreciated! Cheers 🍻

Hokay, so firstly those are two separate codes, 06 and 0A, secondly, there's not really really a standard code list because manufacturers mix and match a bit, and add their own codes, so if you can get a manufacturer supplied list for board revision and bios revision, it will be spot on, but otherwise there's a bit of guessing and mental interpolation between standard code tables.

Looking at this set... http://www.bioscentral.com/postcodes/awardbios.htm

I think, reading the sticker, ISA/PCI 586 BIOS that's it's gonna be close to the ISA/EISA codes given there. It's gonna be the latest code wedging it, so 0A which is given as "Set interrupt table; Initialize keyboard; Detect keyboard controller" ... now your KBC looks to be socketed... so try pulling it, scrubbing the pins and socket with alcohol, re-inserting firmly, and see if we get stuck on 0A again.

maxtherabbit wrote on 2021-12-01, 20:13:

Anonymous Coward wrote on 2021-12-01, 18:34:

TMC/Mycomp

I've got a dual socket 8 board from them that's been a huge headache, was everything they made just bargain bin shit?

Slow, problematic, difficult to configure, random incompatibilities

Sadly though not as “cheap “ as you would want for such troubles.

The board I had lost the onboard serial ports after installing windows 95 and no Matter of resets or reconfiguring would bring them back, not even a plain dos install.

BitWrangler wrote on 2022-01-27, 21:14:

Hokay, so firstly those are two separate codes, 06 and 0A, secondly, there's not really really a standard code list because manufacturers mix and match a bit, and add their own codes, so if you can get a manufacturer supplied list for board revision and bios revision, it will be spot on, but otherwise there's a bit of guessing and mental interpolation between standard code tables.

Looking at this set... http://www.bioscentral.com/postcodes/awardbios.htm

I think, reading the sticker, ISA/PCI 586 BIOS that's it's gonna be close to the ISA/EISA codes given there. It's gonna be the latest code wedging it, so 0A which is given as "Set interrupt table; Initialize keyboard; Detect keyboard controller" ... now your KBC looks to be socketed... so try pulling it, scrubbing the pins and socket with alcohol, re-inserting firmly, and see if we get stuck on 0A again.

Thanks for the pointers! It makes a whole lot more sense now reading the POST CODE display 😀

Yes the more manuals and tables I look at for Award BIOS from that era (ISA/EISA or ISA/VLB-to-PCI in this case) points at the keyboard controller detect/initialization. I sure hope it has nothing to do with the interrupt vector initialization.

I will lift the keyboard controller dip-chip, give everything a thorough cleaning and probe any traces I can follow.

Could it be sensitive to the keyboard itself? Sounds far fetched, but I will try without it being connected. Using a keyboard from early 2000s with both USB and PS/2 connector to DIN adapter.

LocalBus wrote on 2022-01-28, 06:12:

Could it be sensitive to the keyboard itself? Sounds far fetched, but I will try without it being connected. Using a keyboard from early 2000s with both USB and PS/2 connector to DIN adapter.

I think it should POST without a keyboard connected, it'll just complain that there's no keyboard present. I think PS/2 and AT keyboard protocols are very similar, so I'd expect a straight through PS/2 -> DIN would have the best chance of working. There should be an initial flash of the keyboard LEDs when power is turned on and the keyboard does its own self test. Then there should probably be another quick flash when the BIOS checks that it can set and unset the LED status, but that'll be further down the POST process.

@LocalBus, If you have an (E)EPROM programmer, can you make a BIOS copy from the EPROM chip?
I would love to poke around in the Award BIOS from this unique board, and I should be able to tell you exactly what the BIOS is doing in POST 0A. 😉

Jan

Chkcpu wrote on 2022-01-28, 12:55:

@LocalBus, If you have an (E)EPROM programmer, can you make a BIOS copy from the EPROM chip?
I would love to poke around in the Award BIOS from this unique board, and I should be able to tell you exactly what the BIOS is doing in POST 0A. 😉

Jan

Hi! I have been planning to get one, could you recommend one that fits the bill? Then I will happily make a BIOS copy for the greater good 😀

TL-866 is the go-to tool for that

stamasd wrote on 2022-01-28, 14:16:

TL-866 is the go-to tool for that

Thanks! Should arrive on Feb-1.

Ok I did some site cleaning around the DIP 40 socket and tried to trace for example the Xtal inputs to the adjacent Xtal and realized that I got continuity on way too many spots 😅

Tried to reassemble and no surprise, no change, still the 0A code. Removing the keyboard controller and it stops at 05 so I think we have narrowed it down for sure.

Then I started measuring adjacent diodes and transistors in diode mode - Bingo! - Q1 is shorted:

EDIT: I probably should not rule out the SMD capacitors causing the short either. Oh well, time for some soldering.

Next up is to identify whether it is of NPN or PNP type (most likely NPN as emitter follower) and luckily Q2 is still healthy so it should serve as a reference.

EEPROM programmer is ordered so I will dump the BIOS as soon as it arrives.

Getting there folks!

LocalBus wrote on 2022-01-27, 20:46:

Finally an update to this topic! […]
Show full quote

Finally an update to this topic!

I did my homework and replaced the Varta 3 battery with a somewhat more modern NiMH counterpart. In fact the old NiCd happily charged up to 3.6V on my hobby charger 😀

Also had to resolder the ceramic decoupling capacitors sitting underneath the CPU package since those where pushing against the CPU itself. Most likely this was a tight fit with the early Gold heatspreader P90 CPU and the somewhat later revision P100 I have in possession protrudes just a tiny bit more.

20220110_175058.jpg20220110_175022.jpg20220110_204808.jpg

Now on to my POST issues ->

With no memory installed or in the wrong memory bank/order I get PC speaker beeps with POST code:

C1BE (which indicates something about memory so fair enough)

20220127_212946.jpg

With SIMM installed (in the assumed correct bank/order) - I tried several combos with the SIMMs I have - I get no beeps but the POST code:

060A (06 is Award BIOS reserved)

20220127_212852.jpg

I have been searching for the 060A POST code but to no avail. Anyone else out there who have observed this 🤔

ROM checksum error maybe?
http://www.bioscentral.com/postcodes/awardbios.htm

It is definitely not a PNP BIOS, it reads the following:

ISA/PCI 586
S/N: 013870745

Any feedback is much appreciated! Cheers 🍻

Now I see your last POST, in particular in my opinion there is an interpretation error, the POST card freezes on 0b and not on 06, what does it mean you can find it in the POST CARD booklet (or online), maybe this is for you it can be useful to understand if there is a problem somewhere in the MB.

*facepalm* yeah, 6 should have top segment lit.

Haha right you are 😀

What about this manual as reference ->

https://www.google.com/url?sa=t&source=web&rc … KYQ09QRT5cysAw2

B : Test CMOS RAM Checksum
C : Initialize Keyboard

The CMOS RAM Checksum must be corrupt after some 25 years on the shelf. But I think I have changed the jumper back and forth to reset the CMOS a number of times? What else to clear this out? Desolder the brand spanking new battery?

CMOS reset is a matter of removing the voltage yes? I.e. the jumper is there to provide continuity for the same?

For sure the shorted area does not help the cause so need to desolder whatever that is causing it, then do another test.

Thanks 😊

Ok, so if we use the Award ISA/EISA BIOS Version 4.0 entry from bioscentral, then with no memory installed it gives C1 BE (thanks PC@LIVE), so it's completed chipset initialisation and fails on memory size check. Which makes sense. Then with memory installed it fails on 0B 0A, so it's completed initialise keyboard and fails on "CMOS Checksum ; video interface initialised" (video memory and video adapter still to come). 0B often seems to be something CMOS related. Q1&Q2 might be something to do with voltage supply for the CMOS?

If you haven't already got it figured out, any chance of photos showing the top and back of the area around those transistors, and of the flat face of the transistor?

[edit: circuit looks a bit like this (from the 82C206 datasheet:

Q1 looks like the PNP in that circuit. So it it's gone short C-E then the battery will be trying to power the board +5V when the board is off.
]