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From: ccc_ldo@waikato.ac.nz (Lawrence D'Oliveiro, Waikato University)
Newsgroups: comp.sys.mac.system
Subject: Re: PPC, IAC, and True Multitasking (tm)
Message-ID: <1273.26d144fa@waikato.ac.nz>
Date: 21 Aug 90 02:28:10 GMT
References: <1990Aug3.040513.14844@d.cs.okstate.edu> <2760@bridge2.ESD.3Com.COM> <13888@cbmvax.commodore.com>
Organization: University of Waikato, Hamilton, New Zealand
Lines: 25

In <13888@cbmvax.commodore.com>, valentin@cbmvax.commodore.com (Valentin
Pepelea) makes a couple of misleading comments:

"There is no such thing as a cooperative scheduler."

Yes there is--it's called MultiFinder (or the Process Manager under
System 7). It's the bit of code that decides which process gets to
run next when the current process calls Get/WaitNextEvent. If that
isn't scheduling, I don't know what is.

"a preemptive operating system will be faster, because it will
perform task switching only when necessary."

Not quite true. A *non-time-sliced* preemptive operating system
will perform task switching only when necessary. A time-sliced
scheduler is liable to cause lots of unnecessary task switches
under conditions which I expect to be quite common on a single-
user system.

Lawrence D'Oliveiro                       fone: +64-71-562-889
Computer Services Dept                     fax: +64-71-384-066
University of Waikato            electric mail: ldo@waikato.ac.nz
Hamilton, New Zealand    37^ 47' 26" S, 175^ 19' 7" E, GMT+12:00
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