Hello,

I also have one of these motherboards and have been digging for information for a few months now. It's interesting because it has a coin cell battery and after searching through pictures on the theretroweb.com I cannot find another mb with one.

Mine is pretty much exactly the same except that its "VER 1.0-004" it came in a case called an CAF PC Master which is not currently posting at the moment as two of the tantalum capacitors have popper near the power plug on the board.

Would you by any chance be able to confirm the capacitor (C118 & C120) values for me as the top half of the caps have blown off.

Sorry I cannot help more, I was just excited to see someone else with the same board.

Cheers

The coin cell battery is for the UMC 82c8167 or MM58167 real-time clock chip (the UMC one is a clone of the MM part by National Semiconductor). This is a very common clock chip for XTs. Typically, this clock chip was found on an add-on card, either a dedicated clock card, or more commonly some kind of multi-I/O card with one serial port (often: optional second serial port), one parallel port and an FDC, possibly also a game port. In case of this mainboard, mostly everything that makes up an Turbo-XT mainboard except for RAM is integrated in the Acer M1101. This leaves a lot of space, so they just put the contents of a typical XT I/O card on the main board, too.

There is a 30MHz quartz oscillator. The only purpose of a 30MHz oscillator in an XT-class machine I know of is driving an 8088 at 10MHz, so there likely is a 10MHz Turbo mode on that board.

For the clock, you should be able to find generic XT clock programs that probe for the most common chips at the most common I/O addresses, and I expect most of those generic programs to support the MM58167 and I expect this mainboard to expose the clock chip at a common I/O address.