Industrial process control requires that event time stamps be close to the correct social (wall clock) time, for correlation with events that were not digitized. Computers at the heart of these control systems were required to run on DC from batteries, and so the real-time clock was derived from a local crystal. (Make that micro-computers. Work was still done with line-frequency-aware computers.)
The system that I helped design had a clock rate adjustment for social time, expressed as one byte. The user was able to adjust the clock rate for the desired accuracy. A clever algorithm minimized the amount of code added to the clock interrupt routine. But, I have only studied one of the elephant's legs. Bill Hawkins _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
