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From: doner@henri.ucsb.edu (John Doner)
Newsgroups: comp.sys.mac.system
Subject: Re: Preemtive/Cooperative multitasking (Re: All about sys 7.0 <long>)
Message-ID: <10206@hub.ucsb.edu>
Date: 29 Mar 91 17:42:48 GMT
References: <0B010004.4k8s8a@outpost.UUCP> <1991Mar29.020730.15872@cs.uoregon.edu>
Sender: news@hub.ucsb.edu
Reply-To: doner@henri.UUCP (John Doner)
Organization: University of California, Santa Barbara
Lines: 26

In article <1991Mar29.020730.15872@cs.uoregon.edu> mings@comix.cs.uoregon.edu (Ming Yau So) writes:
=In article <0B010004.4k8s8a@outpost.UUCP> peirce@outpost.UUCP writes:
=>In article <91085.161852EHYOUNK@MTUS5.BITNET>, EHYOUNK@MTUS5.BITNET writes:
=>> 
=>> I completly agree with the statement that Mac OS should have prementive
=>> multitasking.. Multifinder is a joke, they is no way to download from a modem
=>> while running another app. Here are some other problems.
...
=I am not the original poster, but here is an example.  Use any of your
=favorite comm. software to download a file, then switch to Finder, and
=copy a floppy.  What do you think will happen ?  The download fails !
=...  Therefore I don't
=think preemtive multitasking would bring any inconvenience to a Mac user,
=indeed, it gives the user more controls.

Preemptive multitasking is pretty much irrelevant to the situation
described.  The reason the download fails is that for PHYSICAL reasons
the disk driver must disable interrupts for rather long periods while
disk operations are in progress.  Those reasons will still exist
whether or not your operating system offers preemptive multitasking.

The cure for the problem is DMA, not preemptive multitasking---the i/o
hardware needs to be able to operate without much cpu intervention.

John E. Doner	doner@henri.ucsb.edu	(805)893-3941
Dept. Mathematics, UCSB, Santa Barbara, CA 93106