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From: oster@lapis.berkeley.edu (David Phillip Oster)
Newsgroups: net.micro.mac
Subject: Re: Closing DAs (and TML questions)
Message-ID: <1213@jade.BERKELEY.EDU>
Date: Tue, 2-Sep-86 16:30:44 EDT
Article-I.D.: jade.1213
Posted: Tue Sep  2 16:30:44 1986
Date-Received: Wed, 3-Sep-86 18:47:11 EDT
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Reply-To: oster@lapis.berkeley.edu.UUCP (David Phillip Oster)
Organization: University of California, Berkeley
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Read David Berry's posting on the subject! Now, some things he left out:
Your desk accessory gets called to process _Control calls.
Control calls come in two flavors: IMMED and queued. 
(You can tell an IMMED one, because the IMMED bit is set in the trap word
in the IO Parameter block.)
IMMED calls must return via an RTS instruction,
all other control calls must return via a JMP to IODone, but leave the
original return address on the stack.

T.M.L. Get this wrong!  The example that comes with the compiler is broken
on this point.

People work on their Macs.  A buggy desk accessory can easily cost someone
a days work.  You have a duty as a Mac programmer to get those bugs out.
The only way to get the bugs out is to have good information.  Buy a copy
of Inside Mac, and get the tech notes or for God's sake have your "about"
message say that you are a dilettante.

--- David Phillip Oster		-- "The goal of Computer Science is to
Arpa: oster@lapis.berkeley.edu  -- build something that will last at
Uucp: ucbvax!ucblapis!oster     -- least until we've finished building it."