"CMOS inoperational system halted" sounds like an error with the RTC to me. Maybe it's simply because the battery is missing ? Try to add a battery to the circuit ?

Interesting board, manufacturer code 1187 is undocumented, if we can find who that is, it'd be pretty cool ! I have never seen that Austek chip on a board before ! Neither that errror.

Could you please dump the bios if you can right now, or dump it when the PC will be working ? That way we can add it to ultimateretro

Austek existed for very short time frame. Asutek developed a cache controller alternative to Intel's.

Cheers,

The "Microcache TM"

I wonder what "CN1" is for. An additional RAM-card?

I will certainly publish the bios rom! I tried to boot now, but I didn't manage to do so. The system keeps failing with the 3 long beeps. After 4h-8h it usually boots up (when there is no battery present).
I've downloaded AFU DOS 4.4 from AMI. Would this be the right tool to dump the BIOS? I don't have a MiniPRO or similar to dump, but if I fail to boot the system I will acquire one and post the dump here.

I added a single brand new Sony CR-2032 to the battery circuit. I tried adding a 1.5V battery (in series) to bump the voltage to 4.5V, but that didn't change the outcome.
The board will often boot when the battery is present.

I wonder what "CN1" is for. An additional RAM-card?

I think so! It would be lovely to find the manual for this board. I will ask the seller if they have more information on it.
BTW, this was the ad https://www.ebay.com/itm/265391155051.

Found a possible match on ultimate retro: https://www.ultimateretro.net/en/motherboards/2091
Layout looks the same.

Anyway, yes the missing/failed tants will mean the power supply voltages will be noisy, which can cause many weird problems. Also, what are you using for the external battery? If the chip under the yellow sticker is a TACT83443: http://www.dosdays.co.uk/media/texas_instrume … 0/datasheet.pdf then pin 63 should be at the battery voltage. Looks like there might be a convenient via next to the pin to measure that voltage.

[edit: actually, not quite a match as the external battery header is in a different place]
[edit: if it is that TI chipset then Vbatt should be between 3-5.5V, so the 4.5V you've tried should be ok, even with a diode drop between battery and chipset]

First step, try a battery on it.

However there's a couple of things I'm not happy with, from the getting an unknown board to exhibit full functionality point of view... i) The 66 Mhz crystal implies that the board is hardwired for 33Mhz, and I don't see enough jumpers in the right areas to be convinced that's settable. Therefore a 25Mhz CPU may be overclocked, which can lead to spurious operation unless carefully tweaked and tuned, or maybe is one of the "losing tickets" i.e. a CPU that won't overclock. ii) The cache at 25ns is a bit on the slow side for 33Mhz operation also, I would prefer to see 20ns in it.. Seems like this board might have been bare at one point and someone just stuck available parts in it, whether they were ideal or not.

snufkin wrote on 2021-12-31, 17:55:

Found a possible match on ultimate retro: https://www.ultimateretro.net/en/motherboards/2091
Layout looks the same.

Yes, this is a 100% match, both on the jumper labels and the location of the components on the board. This is the board OP has.

You folks are AWESOME! Thank you so much for all the replies so far.

snufkin wrote on 2021-12-31, 17:55:

Found a possible match on ultimate retro: https://www.ultimateretro.net/en/motherboards/2091 Layout looks the same. […]
Show full quote

Found a possible match on ultimate retro: https://www.ultimateretro.net/en/motherboards/2091
Layout looks the same.

Anyway, yes the missing/failed tants will mean the power supply voltages will be noisy, which can cause many weird problems. Also, what are you using for the external battery? If the chip under the yellow sticker is a TACT83443: http://www.dosdays.co.uk/media/texas_instrume … 0/datasheet.pdf then pin 63 should be at the battery voltage. Looks like there might be a convenient via next to the pin to measure that voltage.

[edit: actually, not quite a match as the external battery header is in a different place]

Wow, that indeed looks like the board I have! Fantastic!
Also, you are right on the spot about the chip under the "003.". It is a TACT83443GPP. I've measured pin 63 (there was a via hole, probed there) against the battery ground (is this the right way?) and it read 1.642V (system turned off). Should I measure it with it on?
This seems wrong, right?

​For battery I'm using a CR2032 on the 4 pin battery header (I've placed the battery + on pin 1).

Hi BitWrangler, thanks for the analysis!

BitWrangler wrote on 2021-12-31, 17:56:

First step, try a battery on it.

I'm using a CR2032, do you think this should work?

BitWrangler wrote on 2021-12-31, 17:56:

However there's a couple of things I'm not happy with, from the getting an unknown board to exhibit full functionality point of view... i) The 66 Mhz crystal implies that the board is hardwired for 33Mhz, and I don't see enough jumpers in the right areas to be convinced that's settable. Therefore a 25Mhz CPU may be overclocked, which can lead to spurious operation unless carefully tweaked and tuned, or maybe is one of the "losing tickets" i.e. a CPU that won't overclock. ii) The cache at 25ns is a bit on the slow side for 33Mhz operation also, I would prefer to see 20ns in it.. Seems like this board might have been bare at one point and someone just stuck available parts in it, whether they were ideal or not.

That's concerning. What would be the ideal approach in your opinion? Should I try to find a 33MHz 386 and replace it? As for the cache, should I try to swap the memory chips?

Sorry for the many questions folks, I'm a complete noob on these 286/386 era boards.

Just tried adding a 1.5v "boost" (LR-44 battery in series). Pin 63 measured 3.0V against the battery ground pin (system off).
When the system is on, pin 63 against pin 204 (GND) reads 4.8V.

3V will do.

The 25 MHz CPU is overclocked by 32% at the moment. This c a n be o.k, but it could also incur instabilities.

Did you test with the Turbo-Switch closed? (This should take care of the overclocking)

majestyk wrote on 2021-12-31, 18:47:

3V will do.

The 25 MHz CPU is overclocked by 32% at the moment. This c a n be o.k, but it could also incur instabilities.

Did you test with the Turbo-Switch closed? (This should take care of the overclocking)

Yes, the turbo switch is closed (and turbo LED is on). Would this be the right approach?

If there´s no difference between Turbo and Non-Turbo mode, then the 25MHz CPU running at 33 MHz is not the problem. At least not at themoment until you have fixed the CMOS error message.

Since there has been considerable battery leakage in the past you should remove both BIOS and Keyboard-Controller and check the traces / vias underneath carefully.

majestyk wrote on 2021-12-31, 18:53:

If there´s no difference between Turbo and Non-Turbo mode, then the 25MHz CPU running at 33 MHz is not the problem. At least not at themoment until you have fixed the CMOS error message.

Makes sense. Thank you for the tip!

majestyk wrote on 2021-12-31, 18:53:

Since there has been considerable battery leakage in the past you should remove both BIOS and Keyboard-Controller and check the traces / vias underneath carefully.

Alright! Thank you! I will do this and once checked, I will post an update here.

I've removed the chips. The traces seem alright!
I tried to boot after re-seating and cleaning the sockets, but the "3 long beeps" remained.

Should I be trying something different?

I'm still suspicious of the missing/cracked tants that you've found. But also might be worth checking the pins on the that 443 closely to check for any soldering issues. From the photo it looks like there's something odd on pins 61&62 which are the crystal connections.

Possibly similar issues in this thread - (Solved) Bios POST error message: CMOS INOPERATIONAL. SYSTEM HALTED.

snufkin wrote on 2021-12-31, 21:48:

I'm still suspicious of the missing/cracked tants that you've found. But also might be worth checking the pins on the that 443 closely to check for any soldering issues. From the photo it looks like there's something odd on pins 61&62 which are the crystal connections.

Those "bridged" pins go right to the 32kHz crystal oscillator, which should be responsible for the RTC timer (normally a 6818A, this one is bundled in the big Ti chip). I bet that's going to be an issue, so fixing it might get the board to boot.