Details of the OpenVMS system time-keeping?
4-2 Time and Timekeeping _____________________________ 4.1.1.1__VAX_hardware_time-keeping details… 4.1.1.1.1 TOY clock This is battery backed up hardware timing circuitry used to keep the correct time of year during rebooting, power failures, and system shutdown. This clock only keeps track of months, days, and time. The time is kept relative to January 1st, at 00:00:00.00 of the year the clock was initiailized. The VAX Time-Of-Year (TOY) clock (used to save the time over a reboot or power failure) is specified as having an accuracy of 0.0025%. This is a drift of roughly 65 seconds per month. The VAX Interval Time is used to keep the running time, and this has a specified accuracy of .01%. This is a drift of approximately 8.64 seconds per day. Any high-IPL activity can interfere with the IPL 22 or IPL 24 (this depends on the VAX implementation) clock interrupts-activities such as extensive device driver interrupts or memory errors are known to slow the clock. ________________________
