The IBM 360 systems starting in 1964 used the power line frequency. (A location in low memory got bumped at 300 counts per second. 5 per cycle on 60 Hz and 6 per cycle on 50 Hz.) I wonder how much the power timekeeping wandered back then relative to today.
Does anybody know what the guys in the power company control rooms do about leap seconds? ------------ Leap seconds started in 1972. I was at Xerox in the late 1970s. At boot time, Altos got the time from a local time server. Altos used the system crystal (5.88 MHz) for timekeeping. Personal Altos were rebooted frequently so it didn't matter if their clock drifted a bit. The time server was packaged with the routers. (We called them gateways.) On the few systems that were up a long time (file servers, routers), we hand tweaked a fudge factor to adjust the clock rate. It wasn't hard to get to a second per week. I think the units for the fudge factor (from a config file) were seconds per day, but it would read at least one digit past the decimal point. I don't remember any mention of leap seconds. When were there enough (Unix?) boxes on the net running NTP and keeping good enough time to notice things like leap seconds? I should go browse the old RFCs and see when the API for telling the kernel about pending leap seconds was published. But somebody may have good stories or folklore. -- These are my opinions. I hate spam. _______________________________________________ LEAPSECS mailing list [email protected] http://six.pairlist.net/mailman/listinfo/leapsecs
