[net.micro.6809] Slow Clock: a problem?

knudsen@ihnss.UUCP (11/02/83)

I'm amazed at how rapidly the time-of-day clock in my Coco OS-9
loses time.  I'd say it loses a minute per hour, or one part
in 60!!  No, I wasn't running any interrupt stuff or even hitting
the disk much -- mostly just perusing the manual and trying out
commands.  Can the 3.58 MC colorburst crystal really be that far
off and still work on  a color TV?  More important, if the
timing is that screwy, how much can we believe the disk RPM
program so nicely supplied by the Shack?  One part in 60 equals
plus/minus 5 RPM, slightly greater than the allowable speed range.
What am I overlooking?   mike k

sdyer@bbncca.ARPA (Steve Dyer) (11/02/83)

I found that my OS-9 loses time, too.

The key here is NOT that the clock is wrong, but that many CoCo OS-9 operations
(like disk I/O) require interrupts to be turned off.  Naturally, when this
happens, the system 'loses time', since its conception of time-of-day is driven
off of the 60hz clock interrupt.  Every 60 clock ticks, the time is incremented
by one second.

My own feeling is that the line clock is suitable for scheduling, but a true
time-of-day clock card is needed if you are looking for accuracy.  What I
would love to see is a multi-function board containing 2 serial ports, one
parallel port, and such a clock.

/Steve Dyer
decvax!bbncca!sdyer