Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version VT1.00C 11/1/84; site vortex.UUCP Path: utzoo!watmath!clyde!bonnie!akgua!sdcsvax!dcdwest!ittvax!decvax!vortex!lauren From: lauren@vortex.UUCP (Lauren Weinstein) Newsgroups: net.micro.pc Subject: more on use of interval timer in PC vs. timing loops Message-ID: <462@vortex.UUCP> Date: Thu, 6-Dec-84 01:03:58 EST Article-I.D.: vortex.462 Posted: Thu Dec 6 01:03:58 1984 Date-Received: Sat, 8-Dec-84 04:51:24 EST Organization: Vortex Technology, Los Angeles Lines: 16 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--