VOGONS


First post, by Bernkastel7734

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Hello,
I found this Octek motherboard on a scrap yard for 10$, and just from first glance I can tell it has got such problems:
1) All the socketed ICs are removed,
2) One resistor is ripped off,
3) 6 Chipset pins are shortened,

Getting a keyboard controller, both BIOS EEPROMs and 146818P CMOS won't be hard, but I have problem when it comes to U35, U11 and U17 sockets
file.php?mode=view&id=127362
file.php?mode=view&id=127361
They are labelled as ' 16L8A' and '16L8B', so judging from parts numbers and pics of that motherboard, but of different revision I think that these sockets ought to be populated with PAL chips.
And here comes my question, since I have no experience when it comes to that. Do I have to program these chips with microcode, or just order such chips and socket them?

I think that the biggest problem are these shortened pins, also as You can see, there is a ripped of resistor near that SMD chip ( labelled as R25).
file.php?mode=view&id=127360
Do anyone of You have a knowledge what should be it's resistance?

Thanks for any help

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Last edited by Stiletto on 2022-01-06, 01:15. Edited 1 time in total.

Reply 1 of 15, by Deksor

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Interesting, your board revision is way different from the one we have on ultimateretro https://www.ultimateretro.net/en/motherboards/5203

Unfortunately we don't have a bios dump for it yet. If anyone here has a bios dump, I am interested too 😀

By the way, yes PAL chips need to be programmed ... Which also means someone needs to dump them, except they're often locked for reading. So the next step is retro engineering of the circuit to try to understand what they were supposed to do and make a program for all of them.

Trying to identify old hardware ? Visit Ultimate Retro - Project's thread The Ultimate Retro project - a stason.org/TH99 alternative

Reply 2 of 15, by Bernkastel7734

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All I was able to found about that exact motherboard so far is this:
https://www.dosforum.de/viewtopic.php?f=1&t=9549
Atleast I am sure that these two sockets near RAM ought to be populated by PAL chips and what is interesting is that the third socket in absend on that motherboard.

Reply 3 of 15, by Deksor

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It seems your board shares a lot in common with that board : https://www.ultimateretro.net/en/motherboards/5180

They have the same chipset and the PAL chips have the exact same stickers, hinting that they may be programmed with the same formula.

Firstly, the chipset being identical, the bios for this board should work on yours so you could already test that.
Then if anyone here has a TL866 and an octek fox M, maybe try to dump your PAL to see if they're readable and post them here ?

Trying to identify old hardware ? Visit Ultimate Retro - Project's thread The Ultimate Retro project - a stason.org/TH99 alternative

Reply 4 of 15, by Bernkastel7734

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Reading that German forum I have found that this motherboard was used in series of German postal PC. I will make an account and try to ask about that PAL and BIOS on that German forum. And I also thought about that PAL and BIOS between these two motherboards can be interchangable.

Reply 6 of 15, by quicknick

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Darn, this brings back memories...

The chip labeled 089-001 seems to be common between our boards, but the similarities end here. The Fox M is also equipped with 090-103 and 090-110, whereas your board has a 090-101 and a mysterious/optional one right next to the battery (board works fine without it, from what I understand following the dosforum.de thread). Nevermind that, I guess I'm too tired. That board also dead as a stone, maybe 3rd PAL is not optional after all...

The chipset pins don't look very bad (un-salvageable) at first glance, but it's hard to tell without higher resolution pictures.

I'll attach the chipset's datasheet here, maybe your board is built according to the reference schematic (Fox M obviously isn't, as it features a third PAL).

Obviously, if you manage to get it going, I'm still very much interested in the content of the 089-001 chip. Although I have amassed a bunch of working Fox M boards, I still want to cross the original one off the "to be repaired" list. 😁

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Reply 7 of 15, by Bernkastel7734

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Thanks for the chipset datasheet.
First, I'm going to fix the chipset pins and missing resistor. I guess someone hit these pins with tip of soldering iron while removing the resistor ( ISA slot is burnt in a way that suggests that someone touched it with something hot).
After that I'll make a schematics of conection of these missing PAL chips and will try to check if they followed the instructions from chipset datasheet.
Oh boy, I feel it's gonna be an adventure.

Reply 9 of 15, by Bernkastel7734

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So, that's the wiring diagram of that third misterous PAL ( u35 near battery solder points)
The markings on PCB is ' 16L8B'

?- neither connected to ISA slot nor to Chipset ( traces not on surface)
(X) - pin number

Will try to find where are '?' pins connected, and also will make such diagrams for these two PAL chips near ram banks, so I can check if they follow schematics from Chipset datasheet.

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Reply 10 of 15, by SpringyCZ

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I just bought exactly the same board. It seams to be fully functional. I was searching for some information about it (wanted to know if 1MB RAM is maximal capacity or if it can be expanded somehow-empty sockets close to RAM chips) and found this thread. I have no skills and equipment to dump the PALs and BIOSes content (are there really three?) but I can ask some of my fellas to do it. It just need some time.

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Reply 12 of 15, by Deksor

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Maybe that kind of thing would help ? https://github.com/DuPAL-PAL-DUmper/DuPAL_Analyzer

The author clearly says it's not a pal dumper, but rather a tool made to analyze a PAL and possibly rebuild one. But that's still better than nothing !

Has anyone used this ?

Trying to identify old hardware ? Visit Ultimate Retro - Project's thread The Ultimate Retro project - a stason.org/TH99 alternative

Reply 13 of 15, by SpringyCZ

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Bernkastel7734 wrote on 2022-04-09, 15:03:

It really seems to be the same board. As mentioned above these PAL chips can be protected, but if You can, please ask someone to dump them.

And what about those BIOSes? I don’t know why there are so many. Anyways, when I have a chance, i let all socketed chips to analyse.

Reply 14 of 15, by quicknick

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Assuming you're asking about the chips with shiny silver stickers on them. The two smaller ones are the main BIOS, in an interleaved fashion (odd+even bytes). Something about the chips being 8-bit wide and the 286 bus being 16-bit.
The other one is the keyboard controller, and although it contains some mysterious code inside, I don't know if it truly qualifies as BIOS.

Reply 15 of 15, by Bernkastel7734

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SpringyCZ wrote on 2022-04-10, 18:56:

And what about those BIOSes?

As mentioned, 286 motherboards often had 2 BIOS EPROMs, one even one odd. The code is just split between these two. And that's the only BIOS chips that need to be dumped, not to mention these PAL chips.