Unknown 486 motherboard, please help to ID it. \ VOGONS

Unknown 486 motherboard, please help to ID it.

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First post, by Xeen

Posted on 2018-07-24, 14:53

Xeen Offline

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Rank: Newbie
Posts: 76
Joined: 2018-06-13, 04:45

Hello everyone,
I came across this motherboard recently which has no manufacturer or model on it, can anyone help me to ID it so that I can find the latest BISO and manual online?

Furthermore, it came with 4 EDO ram sticks which are 32MB in total and always gives "ON BOAR PARITY ERROR - ADDR (HEX) = (OOOO:0002) SYSTEM HALTED" error every time I save BIOS changes. If the error shows up then I can't get into BIOS anymore until clear BIOS settings by removing CMOS battery...

After removing CMOS battery several times I figure out that I can bypass the error by disabling "Memory Parity Error Check", but can it cause other issues like instability?

Can I clear BIOS without removing the battery, these jumpers look suspicious?

Reply 1 of 5, by jesolo

Posted on 2018-07-24, 14:55

jesolo Offline

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Location: South Africa

Can you perhaps post a screen shot of the POST screen (where it displays the BIOS ID string at the bottom of the screen)?

Reply 2 of 5, by fitzpatr

Posted on 2018-07-24, 16:11

fitzpatr Offline

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Joined: 2016-10-30, 06:50
Location: Ontario, Canada

https://stason.org/TULARC/pc/motherboards/A/A … -486-V433S.html

The A at the bottom left of the board indicates that it is an AOpen/Acer board.

MT-32 Old, CM-32L, CM-500, SC-55mkII, SC-88Pro, SC-D70, FB-01, MU2000EX
K6-III+/450/GA-5AX/G400 Max/Voodoo2 SLI/CT1750/MPU-401AT/Audigy 2ZS
486 Build

Reply 3 of 5, by Xeen

Posted on 2018-07-25, 04:31

Xeen Offline

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Joined: 2018-06-13, 04:45

Thanks so much for the link it is my board. However, it most unlikely has 32 MB ram for just 4 sticks installed based on the spec. Can it be the reason for the issue?

Reply 4 of 5, by fitzpatr

Posted on 2018-07-29, 17:58

fitzpatr Offline

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Posts: 419
Joined: 2016-10-30, 06:50
Location: Ontario, Canada

The sticks that you are using contain 2 1M(b)x4 chips. This means that each stick of yours is 1MB, for a total of 4MB. (32Mb, as it happens) b = bit, B = byte (8 bits).

The cause of the Parity error is that the manual specifies "1M x 9". The 9 indicates sticks of RAM with 9 Chips. 8-chip RAM is non-parity, 9-chip RAM is Parity. Later sticks condensed this down to 2-chip (non-parity, which you have), and 3-chip (Parity.

Since this motherboard seems to want Parity RAM, I'd look for 30-pin SIMMs with either 3 or 9 chips.

MT-32 Old, CM-32L, CM-500, SC-55mkII, SC-88Pro, SC-D70, FB-01, MU2000EX
K6-III+/450/GA-5AX/G400 Max/Voodoo2 SLI/CT1750/MPU-401AT/Audigy 2ZS
486 Build

Reply 5 of 5, by Xeen

Posted on 2018-07-30, 04:55

Xeen Offline

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Rank: Newbie
Posts: 76
Joined: 2018-06-13, 04:45

Thanks for the elaboration, is it necessary to use Parity RAM? It seems boot okay after disabling "Memory Parity Error Cehck" in BIOS.

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