Specifications

CoreModule/PC Technical Manual
3-10
3.8 SETTING THE REAL TIME CLOCK
In a PC-compatible computer, the time and date are kept current by the ROM-BIOS. They are
updated by the "timer tick", an interrupt that occurs approximately 18.2 times per second. These
values must be initialized each time the CoreModule/PC is turned on. This can be done manually
using the DOS TIME and DATE commands, or by loading the contents of the battery-backed real
time clock. The real time clock maintains the correct time and date while the computer is off if a
backup battery is attached. Chapter 2 covers how to attach a battery.
A utility program, XTCLK, is provided on the utility disk. It passes the contents of the battery-
backed clock to DOS to set the system time and date. The program is described in Appendix A.
Note
The hardware used to implement the real time clock is unique
to the CoreModule/PC. Always use the provided software
utility or ROM-BIOS functions to access the real time clock.