Yes, the whole PDP-11 line used line frequency to update the real-time clock. DEC had a real-time operating system, very useful for emulation of analog process control functions. Of course, an RTOS is more than just the clock.
We lost that anchor to real time in the interval between the PDP-11 and NTP or SNTP when the microprocessors took over. All crystal clocks; time of day (social time) set by anybody with a wristwatch. Bill Hawkins -----Original Message----- From: paul swed Sent: Saturday, December 12, 2009 10:09 PM Talk about dusting off the old brain cells. I seem to remember that the PDP 11/23s did indeed allow the use of the 60 hz as an interrupt for precision timing if that can actually be said. The data general nova 1200 also. Boy thats exposing ones age. On Sat, Dec 12, 2009 at 8:29 PM, Colby Gutierrez-Kraybill < co...@astro.berkeley.edu> wrote: > > I'm trying to get to the bottom of whether or not any computing equipment > made around the advent of UNIX systems (or any time-slicing system) used the > mains cycles of 60Hz as phase lock for the internal system clock. My guess > is that perhaps they did not as the computing logic is DC based, but, I have > memories of using an 68000 based UNIX system that I thought had its internal > clock based off of the 60Hz mains... Not sure the vendor anymore. > > Thanks, Colby > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
