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From: es1@cunixb.cc.columbia.edu (Ethan Solomita)
Newsgroups: comp.sys.amiga.misc,comp.sys.amiga.advocacy
Subject: Re: How do we change the scheduler? (Was Re: Multitasking at home...)
Message-ID: <1991Jan14.221532.4431@cunixf.cc.columbia.edu>
Date: 14 Jan 91 22:15:32 GMT
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In article <JIMB.91Jan14143121@pogo.ai.mit.edu> jimb@pogo.ai.mit.edu (Jim Blandy) writes:
>
>A Mac running the Multifinder has non-preemptive multitasking; each
>task voluntarily gives up control.  The Amiga does preemptive
>multitasking; a task may be stopped at any time.
>
	Problem is, most tasks DON'T give up control. Mac
programs have to be written to purposely give up control and many
are still written badly enough to not work, MicroSoft being one
of the worst culprits. The Amiga's MAIN advantage is that it is
built into the system. You just don't do anything unusual with
your program and it'll multitask very nicely. Yes, Apple is
constrained by backwards compatibility, but I hate being
constrained by backwards operating systems! 8)

>The Amiga exec does provide system calls to disable and re-enable
>multitasking; I imagine this is because Commodore would rather provide
>a system call than have people non-portably hack it when they need it,
>but one doesn't need these calls in normal Amiga programming.

	Actually it can be necessary for normal programming, and
Commodore does give examples of programming where it is
necessary. If you need to play with any of the system lists, such
as task lists, message ports, and you don't use Commodore
supplied functions, you'll need forbid/disable. Also, if you are
changing some pointers in your internal structures, such as your
screen and windows structures, you have to make sure that it
never leaves a usable state, otherwise you need to stop
multitasking.
	-- Ethan

	"Don't forget the importance of the family. It begins
with the family. We're not going to redefine the family.
Everybody knows the definition of the family. ... A child. ... A
mother. ... A father. There are other arrangements of the family,
but that is a family and family values."

	-- Dan Quayle, of course. Our beloved Vice President.
	It's just too easy!