I have an old mainboard, type PWA-286C, running a 10 MHz Intel 80286. I have no manuals, so I am looking for documentation on it.

I am especially wondering if there is a connector for the real time clock battery. Maybe J21? Also what the voltage for it might be. Also wondering about the large J17 near the CPU.

Additional question: The board is running a Phoenix 3.0 BIOS. I guess there is no internal setup program? Can I use GSETUP on this?

Here is a picture:



1 Answer 1


The RTC on your motherboard is the Hitachi HD146818P DIP chip located SouthEast of the CPU in your photo. According to the datasheet it uses a backup battery voltage that is nominally 3VDC. I suspect that J21 is probably the battery jack, but I don't see any indication of polarity.

J17 is a 34-pin connection that is likely for the built-in Floppy Disk Controller (FDC). Use it to connect two standard PC floppy drives.

  • Concerning the floppy controller: That's neat. Will make booting it simpler. I just ordered a USB drive floppy emulator, since I don't have any drives or floppies anymore. Concerning the RTC: Do you think it makes sense to probe the pins of J21 and the IC with a multimeter to see what is connected to which pin? Using the datasheet of the HD146818P as a guide.
    – Arne
    Commented Apr 4, 2018 at 7:00
  • J17 looks like a 3-pin header. So if you can find the correct PC battery replacement it should only connect one way. But it is definitely a good idea to confirm which pin is GND/Vss with a multimeter too.
    – Brian H
    Commented Apr 4, 2018 at 13:25

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