In message <[email protected]>, Hal Mu rray writes:
>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. It used to be pretty good, because people used synchronous motors to drive clocks so the power companies tried to keep the long-term frequency correct. In Denmark they usually lost a couple of seconds during the day and gained them back during the night, similarly they lost half a minute over winter and gained it back over summer. After deregulation nobody gets paid to keep the long term frequency, so mains is no good, actually down-right bad, for timekeeping anymore. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [email protected] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ LEAPSECS mailing list [email protected] http://six.pairlist.net/mailman/listinfo/leapsecs
