I have installed in my Altair, a Compu/Time CT-102 real-time-clock board which was purchased in 1979. This board supports a battery backup option. This is basically a "digital clock" chip with BCD outputs (intended to drive BCD to 7-segment decoders) on an S-100 board. The fact that it is a chip intended for a clock display gives rise to certain odd characteristics: - Certain leading digits read 'F' instead of '0' for a zero value - this is because 'F' == Blank on the 7-segment decoder. - To set the time, the software has to "hold down" Fast and Slow time set buttons, and watch the time value scroll by until the desired setting is reached - just the way a human would set a digital clock from that era. Photos of this card and scans if it's documentation are available in the Altair section on my site. Regards, Dave -- dave04a (at) Dave Dunfield dunfield (dot) Firmware development services & tools: www.dunfield.com com Vintage computing equipment collector. http://www.parse.com/~ddunfield/museum/index.html