[net.micro.pc] more on use of interval timer in PC vs. timing loops

lauren@vortex.UUCP (Lauren Weinstein) (12/06/84)

After some checking, it turns out that there are even more
reasons NOT to directly use the interval timer:

1) Of the three ports on the unit, one handles dynamic refresh.
2) Another port is connected directly to the audio speaker.
3) The last provides "real time clock ticks" at a fixed
   rate of approx. 18.2/sec on the "real" PC/XT/AT.  There is no
   guarantee of the same rate on PC clones of various sorts.

Given that none of these ports can be "diddled" without damaging
other important functionality, and given that a fixed interrupt
rate of approx. 18.2 isn't terribly handy (or even USABLE) in
many applications, this still leaves only timing loops in a
large number of situations...

--Lauren--

gnome@olivee.UUCP (12/11/84)

Timing loops will cause problems pretty quickly on the ATT PC 6300.
It's based on an 8086 and is clocked faster.

Sorry gang.