8254 timer usage under Sys V/386 R3.2?
Andy Pfiffer
apfiffer at admin.ogi.edu
Fri Feb 1 17:02:41 AEST 1991
I'd like to be able to program and poll one of the timers on the 8254
Programmable Interval Timer under a vanilla System V/386 R3.2. I have
no difficulty accessing the ports, but I'm not certain how UNIX uses them.
There are three 1.19 MHz timers on the chip. My guesses:
Timer Function
0 100Hz clock interrupt
1 DRAM refresh (about 66 KHz)
2 beep & buzz
Are these correct?
Thanks.
--
Andy Pfiffer (503) 645-1886 apfiffer at admin.ogi.edu
Formerly w/ Cogent Research, Formerly w/ Topologix, Formerly w/ Theory Center.
"To determine where to resume execution upon leaving the trap handler, examine
the instruction at address fir - 4.
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