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From: waldman@husc4.HARVARD.EDU (benjamin waldman)
Newsgroups: comp.sys.mac
Subject: Re: How to launch an application
Message-ID: <1828@husc6.UUCP>
Date: Sat, 2-May-87 14:01:52 EDT
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Posted: Sat May  2 14:01:52 1987
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Keywords: launch


	
	In posting 1405, someone asked how to start an application from
assembly language.  I mailed him an answer directly, but since the same
question has been asked again, I'll post a response.
	Basically, there are two ways to start an application.  You can
use the _Launch trap ($A9F2, I think), or the _Chain trap.  Both start a
new application, but while _Launch clears the application heap, _Chain
does not, enabling one application to pass information to a second.
The Finder uses _Launch.
	Before you use either of these traps, the following must be set up.
(A0) should be a pointer to the name of the new application, a Pascal
string, I presume.  The value in 4(A0) determines which screen and sound
buffers are used.  A 0 means use the main screen and sound buffers, any
positive value means use the alternate sound and main screen buffers, and
any negative value means use the alternate screen and alternate sound buffer.
For the sake of compatibility, only the main screen and sound buffers should
be used, since not all Macs have the alternate buffers  (I think that this is
what got Megaroids into trouble).
	Anyway, I think that this piece of code will serve as a demonstration.
I haven't used it or tested it, but I think it should work.

	String_Format 3   (make sure that strings are Pascal strings)
buffer:	ds.l 2
name:	dc.b "My application"

	lea buffer(A5),A0
	lea name,A1
	move.l A1,(A0)
	clr.l 4(A0)
	_Launch

	I hope this is helpful.
					
					Benjamin Waldman
					waldman@husc4.harvard.edu