Path: utzoo!attcan!uunet!decwrl!bacchus.pa.dec.com!shlump.nac.dec.com!mountn.dec.com!minow
From: minow@mountn.dec.com (Martin Minow)
Newsgroups: comp.sys.mac.programmer
Subject: Re: High-resolution timing?
Message-ID: <1825@mountn.dec.com>
Date: 7 Aug 90 14:46:23 GMT
References: <1822@mountn.dec.com>
Reply-To: minow@bolt.enet.dec.com (Martin Minow)
Organization: Digital Equipment Corporation
Lines: 34

In article <1822@mountn.dec.com> minow@bolt.enet.dec.com (me) asks about
high-resolution timing.  Thanks for several useful responses:

-- The TimeManager (Inside Mac IV and TechNote 180) supports 1 msec
   resolution timing.  You can install a task that merely updates a
   global counter each time it is called.  There might be problems
   if I/O operations block the interrupt.

-- Mike Tarr described a millisecond timer support package:
 
    There is a millisecond timer that works on all macs -- the reference is
    Behavior Research Methods, Instruments, and Computers, 1989, 21 (5), pp
    540-547 and the title is: Millisecond timing on the apple macintosh:
    updating drexel's millitimer. They distribute a disk with full sources.
    It seems to work pretty well -- but there is no simple way to link these
    to a keypress...

-- Think C has a "VIA_timer.c" (in the library source) that, according to
   comments in the code, gives 1.28 microsecond resolution.  This is used
   by the Think C profiler.  I'm not certain if it will work for, say,
   an INIT or driver.  Nor am I sure it will work on "all" Mac's, including
   future systems.

Thanks to the following for the useful help (in order of arrival).

pers@ifi.uio.no		Per Siljubergsaasen, Institute of Informatics,
			University of Oslo
andyc@ai.mit.edu,	Andrew D. Christian
tarr@cs.yale.edu	Mike Tarr
ba0k+@andrew.cmu.edu	Brian Patrick Arnold
olson@endor.harvard.edu	Eric K. Olson

Martin Minow
minow@bolt.enet.dec.com