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From: lipa@polya.Stanford.EDU (William J. Lipa)
Newsgroups: comp.sys.mac,comp.sys.mac.programmer
Subject: Re: multitasking and IPC
Message-ID: <5724@polya.Stanford.EDU>
Date: 18 Dec 88 22:20:31 GMT
References: <1988Dec16.191309.21623@cs.rochester.edu> <326@internal.Apple.COM> <264@berlin.acss.umn.edu> <329@internal.Apple.COM>
Reply-To: lipa@polya.Stanford.EDU (William J. Lipa)
Organization: Stanford University
Lines: 15

I wonder if it would be possible for Apple to define a routine to let other
applications have a time slice which could run at interrupt time. For example,
if EventAvail was removed from the list of traps that may move or purge
memory, an application writer could install a VBL task which did nothing except
call EventAvail 60 times a second. Since EventAvail is (I believe) one of the
traps which allows context-switching, this would give programmers an easy way
to add preemptive multi-tasking to their applications.

Since each application runs in its own heap, it shouldn't have its own memory
moved or purged even if another application is run. I suppose you would get
into trouble if your app was allocating a block in the system heap, though.
Might there be some way around this?

Bill Lipa
Bitnet: lipa%polya@stanford