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Identifying an ADC Opti Motherboard (SOLVED)

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First post, by zakurowrath

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This is my 386 project im working on. A good friend of mine gave me this old motherboard about 14 years ago and ever since then, I've never been able to find any information about it. It has an ADC warranty sticker from October 1992, an AMD 386 SX/SXL-33 running underclocked at 25 MHz (50 MHz Crystal Oscillator oddly enough) along with a 20 MHz 387 Math Processor. The BIOS is an American Megatrends with a date of December 12, 1991 (30-0300-001117-00101111-121291-OPSXPI-M) The main chips on the board seem to be an Opti F82C206 & Opti 82C283. The three ID Numbers on the board are P9HN COPYRIGHT 1992 85-05-0100, SM-4328-1 923201 & WTF-920605-00. Would anyone have a motherboard close to this or a manual for this series? I would love to know what some of the jumpers on the board do like the J5 MONITOR next to the 386SX BIOS, the J1 "DISCHANGE" (did the mean discharge?) 3 pin jumper & what to do with the 4 pin EXT-BATTERY header which tests ++-- (1234). Also would love to know how much RAM the board can handle without trial and error. I thank anyone with any information about this mystery motherboard. 😊

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Last edited by zakurowrath on 2018-04-07, 06:40. Edited 2 times in total.

Reply 2 of 3, by zakurowrath

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konc wrote:

It looks exactly like this one to me. Even though it's P9-HD I see no difference from your P9-HN. In any case you can make out all the jumpers from it.

You are amazing Konc, thank you so much 😁

Interesting the board still POSTs without the CMOS jumper in place and is in colour without the monitor jumper in place. 16MB of RAM max, hmm still enough to run Windows 95 if needed. Just need an external battery or modified circuit with a diode for a soldered battery. Hope this helps someone in the future that has a similar board, guessing mine is just a later revision. Thank you so much again!

Reply 3 of 3, by jade_angel

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Fair warning, Win95 will be agonizingly slow on a 386SX, even with enough RAM, if my recollections serve me right. But yeah, it will work in a pinch.

Main Box: Macbook Pro M2 Max
Alas, I'm down to emulation.

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