The OPTi Viper board is a beauty. It's an Acer AN5C, which I found by googling those numbers at the top right of the board: 48.58201.002 94151-2x

Not sure how much that's going to help you as it's not in TH'99 or Elvhb or any of the other usual places for manuals.

There's a thread about it (from 2006) on rom.by, but apart from dead links to pics and a dump of the BIOS, the conclusion there was to go try contact Acer, with no signs of success:
http://computer-master.by/oldromby/topic11296.html

That said, Acer was always remarkably good at documenting the board on the PCB silkscreen, and this appears no exception. All vital settings seem to be there and documented. Another nice touch: the inevitable DS12887 is socketed, so easily replaceable. A dead RTC might be the cause of it not booting. Do you have a POST-card, and if so, what does it say when you want to boot?

Edit:
The other board is one of a family of OPTi 495SX-based 386/486 combo boards. I have a similar one with exact same components (up to the unused pads for onboard CPU) but in a different layout. The original BIOSs on these boards were a pain, but there's a MR-BIOS for the 495SX that works on all of them and is vastly, vastly superior. In my case the original BIOS initialized POST fine, allowed entry into setup but hung when trying to actually boot from any drive. The MR-BIOS fixed that. To upgrade BIOS, you need an E(E)PROM of the correect size (512kb iirc) and a programmer.

dionb wrote:

A dead RTC might be the cause of it not booting. Do you have a POST-card, and if so, what does it say when you want to boot?

Are you sure? what if I remove it from the socket?
I have two debugger cards but could never get them to work properly. I will try again later.
Nothing but a dead blank screen...

dionb wrote:

Edit:
The other board is one of a family of OPTi 495SX-based 386/486 combo boards. I have a similar one with exact same components (up to the unused pads for onboard CPU) but in a different layout. The original BIOSs on these boards were a pain, but there's a MR-BIOS for the 495SX that works on all of them and is vastly, vastly superior. In my case the original BIOS initialized POST fine, allowed entry into setup but hung when trying to actually boot from any drive. The MR-BIOS fixed that. To upgrade BIOS, you need an E(E)PROM of the correect size (512kb iirc) and a programmer.

Would you take a good shot from your board? mine has some missed chips.

RiP wrote:

[...] Are you sure? what if I remove it from the socket? I have two debugger cards but could never get them to work properly. I […]
Show full quote

[...]
Are you sure? what if I remove it from the socket?
I have two debugger cards but could never get them to work properly. I will try again later.
Nothing but a dead blank screen...

Behaviour of motherboards with RTC when the RTC is dead can be all over the place. Generally, they just behaves like a board with battery where the battery is dead (i.e. boots normally, but loses settings as soon as power goes off), but there are ones that display an error and refuse to boot (many IBM PS/2 systems...), and I have at least one board, an ECS 486 EISA board, where the system won't do anything at all, even start POST, without working RTC battery. Come to think of it, a lot of Apples have the same behaviour with dead PRAM battery, like the iMac G4 I picked up last Friday...

As for the cards, theoretically you can figure out a lot from the numbers displayed on them. In practice 95% of what I get out of them is simply whether the system is doing anything at all. If not, there's something very fundamental wrong. If it does start cycling through numbers, it's usually something more trivial. So long as your cards show something you can get that info out of them.

Would you take a good shot from your board? mine has some missed chips.

Bad news: my decent camera is dead and my phone cam is really crap.
Good news: I looked through my archives and recalled I picked up a very similar board at the same time (in a huge haul a year ago). I sold it soon after, but I still have the photograph. Turns out it's identical to yours:
https://tweakers.net/ext/f/crycQNjfk7tmhlEyElhzEYTX/full.jpg

However I don't see what chips you are missing. Only empty sockets I see on yours are for four of the eight cache chips. That can be correct, depending on the cache config.

dionb wrote:

Behaviour of motherboards with RTC when the RTC is dead can be all over the place. Generally, they just behaves like a board with battery where the battery is dead (i.e. boots normally, but loses settings as soon as power goes off), but there are ones that display an error and refuse to boot (many IBM PS/2 systems...), and I have at least one board, an ECS 486 EISA board, where the system won't do anything at all, even start POST, without working RTC battery. Come to think of it, a lot of Apples have the same behaviour with dead PRAM battery, like the iMac G4 I picked up last Friday...

As for the cards, theoretically you can figure out a lot from the numbers displayed on them. In practice 95% of what I get out of them is simply whether the system is doing anything at all. If not, there's something very fundamental wrong. If it does start cycling through numbers, it's usually something more trivial. So long as your cards show something you can get that info out of them.

Well, I removed the VGA card and now I can hear a short beep every 30 seconds like a loop!
Now what to do? Try to rework the RTC? and what was wrong with the VGA cards?
http://www.ardent-tool.com/misc/rework_dallas_rtc.html

dionb wrote:

Bad news: my decent camera is dead and my phone cam is really crap. Good news: I looked through my archives and recalled I picke […]
Show full quote

Bad news: my decent camera is dead and my phone cam is really crap.
Good news: I looked through my archives and recalled I picked up a very similar board at the same time (in a huge haul a year ago). I sold it soon after, but I still have the photograph. Turns out it's identical to yours:
https://tweakers.net/ext/f/crycQNjfk7tmhlEyElhzEYTX/full.jpg

However I don't see what chips you are missing. Only empty sockets I see on yours are for four of the eight cache chips. That can be correct, depending on the cache config.

Mine has 2 missed chips in the middle of the board between the VLB brown slots 😢

RiP wrote:

[...] Well, I removed the VGA card and now I can hear a short beep every 30 seconds like a loop! Now what to do? Try to rework t […]
Show full quote

[...]
Well, I removed the VGA card and now I can hear a short beep every 30 seconds like a loop!
Now what to do? Try to rework the RTC? and what was wrong with the VGA cards?
http://www.ardent-tool.com/misc/rework_dallas_rtc.html

What VGA card? Sounds like either board or monitor didn't like the card. I'd recommend testing with the simplest ISA known-good VGA you have. If it's not known-good, test it in another system first.

As for rework vs buying new - DS12887 can be bought new (Maxim, who took over Dallas, still makes them). Don't buy on eBay (you will probably get another old empty one), but from a reputable electronics supplier (think Mouser in US, Reichelt in DE etc). I'm too lazy and too messy to bother with reworking one of those, I save the effort for DS1387 modules that are no longer in production.

Mine has 2 missed chips in the middle of the board between the VLB brown slots 😢

Wouldn't be too concerned, I remembered the name now: AUVA CAM 33

Here's the exact page for your version:
http://www.uncreativelabs.de/th99/m/I-L/31375.htm

Look up U38 and U39:

VESA SLOT (S2 & S3) MASTER/SLAVE CONFIGURATION […]
Show full quote

VESA SLOT (S2 & S3) MASTER/SLAVE CONFIGURATION

Jumper / Master/Slave / Slave only

[...]

U29 (PAL socket) / Installed / N/A
U38 (PAL socket) / Installed / N/A

So missing the two PAL chips, your VESA slots 2 and 3 are slave-only. Not ideal, but perfectly usable. Whatever is stopping you booting, that's not it. Note all the other jumpers that need to be set for slave-only. If some of those are wrong it might explain a thing or two.

dionb wrote:

What VGA card? Sounds like either board or monitor didn't like the card. I'd recommend testing with the simplest ISA known-good VGA you have. If it's not known-good, test it in another system first.

Wow, it worked with Trident 8900D ISA 😳
But failed with Realtek ISA, SiS 305 PCI, Trident 9750 PCI 😕
I remember it came with S3 PCI.

dionb wrote:

Wouldn't be too concerned, I remembered the name now: AUVA CAM 33 […]
Show full quote

Wouldn't be too concerned, I remembered the name now: AUVA CAM 33

Here's the exact page for your version:
http://www.uncreativelabs.de/th99/m/I-L/31375.htm

Look up U38 and U39:

VESA SLOT (S2 & S3) MASTER/SLAVE CONFIGURATION […]
Show full quote

VESA SLOT (S2 & S3) MASTER/SLAVE CONFIGURATION

Jumper / Master/Slave / Slave only

[...]

U29 (PAL socket) / Installed / N/A
U38 (PAL socket) / Installed / N/A

So missing the two PAL chips, your VESA slots 2 and 3 are slave-only. Not ideal, but perfectly usable. Whatever is stopping you booting, that's not it. Note all the other jumpers that need to be set for slave-only. If some of those are wrong it might explain a thing or two.

Big thanks!

Conflicts all over the place... that awful CMD IDE controller could be to blame. Disable if at all possible. But this mainly looks like default settings of the board are the problem, so sorting out the RTC would definitely be the next step.

What kind of PAL chips should I use for the older motherboard?

RiP wrote:

What kind of PAL chips should I use for the older motherboard?

I found this but still not sure:

https://arstechnica.com/civis/viewtopic.php?f=12&t=951237

They're PALs. The "P" stands for Programmable. The chip alone won't help you without the code and getting that isn't straightforward. Read here:

PALs are programmable logic devices. You program them with very basic logic functions chains of AND, OR, XOR etc. etc. written i […]
Show full quote

PALs are programmable logic devices. You program them with very basic logic functions chains of AND, OR, XOR etc. etc. written in a high level language.

You will need the contents of the PAL chips. Without that you'll have to reverse engineer their function. You will probably never be able to read them to extract there program as they will have been programmed with the protection bit set (making them effectively write only).

You'll need something like PALASM (Assembler of code for PAL chips) to produce JDEC files and then a PAL programmer like a JTAG device depending on the type of PAL chip.

There is 99.99% NO chance to get the code from these PALs you'll have to either give up, reverse engineer them (not impossible due to their capacity and uber basic boolean functionality) or find the original creator. There is a very, very slim chance they are not protected.

But let's step back a bit: why are you so focused on enabling multiple VLB masters? (which is the only thing the PALs do). Before going down that rabbit hole, I'd thoroughly recommend getting the board working otherwise. Or have you already managed that?

Yes, the board works fine now.
Do you have its updated BIOS?

I found another board ( 486VLWB ) which is very similar to the old one but it has crystal oscillator and different BIOS =/

RiP wrote on 2019-12-28, 16:09:

Yes, the board works fine now.
Do you have its updated BIOS?

Ah, sorry, missed this one.

Yes, it's linked here on Vogons:
Re: How about a MR-BIOS ROM file repository?

That leads to:
http://www.mediafire.com/file/icf36l68bw8kh7m … R-BIOS_v160.zip

RiP wrote on 2020-01-09, 20:18:

I found another board ( 486VLWB ) which is very similar to the old one but it has crystal oscillator and different BIOS =/

Not sure that '486VLBWB' is the name of the board. In any event, I can't make out chipset on the pics, so not much I can say here. Could you make a high-res pic of the whole board?

Here you are: https://i.imgur.com/tClKs4k.jpg

dionb wrote on 2019-12-15, 14:00:

The original BIOSs on these boards were a pain, but there's a MR-BIOS for the 495SX that works on all of them and is vastly, vastly superior. In my case the original BIOS initialized POST fine, allowed entry into setup but hung when trying to actually boot from any drive. The MR-BIOS fixed that.

Do you mean booting from hard disk? Mine boot fine from floppy disk but haven't tried hard disk.

I could copy those two PAL chips too:

RiP wrote on 2020-01-12, 14:16:

Here you are: https://i.imgur.com/tClKs4k.jpg

That is very similar, should work with same MR-BIOS.

Do you mean booting from hard disk? Mine boot fine from floppy disk but haven't tried hard disk.

Mine wouldn't boot from anything (HDD, FDD) with the old BIOS. Just hung there after POST. Tried multiple IDE, SCSI and floppy-only controllers. None made a bit of difference. Almost certainly a bad image.

I could copy those two PAL chips too:

That's very interesting. Didn't they have the security bit set?

dionb wrote on 2020-01-12, 15:20:

Mine wouldn't boot from anything (HDD, FDD) with the old BIOS. Just hung there after POST. Tried multiple IDE, SCSI and floppy-only controllers. None made a bit of difference. Almost certainly a bad image.

I feel your ROM was corrupted. Did you test with different memory modules?

dionb wrote:

That's very interesting. Didn't they have the security bit set?

Hopefully no 😀

RiP wrote on 2020-01-12, 21:19:

dionb wrote on 2020-01-12, 15:20:

Mine wouldn't boot from anything (HDD, FDD) with the old BIOS. Just hung there after POST. Tried multiple IDE, SCSI and floppy-only controllers. None made a bit of difference. Almost certainly a bad image.

I feel your ROM was corrupted. Did you test with different memory modules?

Yes, nothing worked. As soon as I flashed that MR-BIOS, everything was fine - with the same SIMMs.