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From: lippin@ragu.berkeley.edu (The Apathist)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Animation
Message-ID: <1991Feb22.202244.10494@agate.berkeley.edu>
Date: 22 Feb 91 20:22:44 GMT
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Lawson.English@p88.f15.n300.z1.fidonet.org (Lawson English) writes:

> I can understand that given protected memory, the supervisor mode,
> etc, that GetTrapAddress may someday be inadvisable for patching, but
> why is its use for finding the trap table entry and jumping directly
> there a future no-no?

I can think of one reason: if the change is made to have applications
run in user mode (a sensible change, which Apple has threatened in the
past) many parts of the operating system will still require supervisor
mode.  A trap instruction switches to supervisor mode; a simple JSR
doesn't.

					--Tom Lippincott
					  lippin@math.berkeley.edu

	"Hell is like a supermarket in other ways, too -- There's an
	 express lane for ten sins or less, and they won't let you
	 take the carts out to the parking lot."
					--Mr. Boffo