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From: hadeishi@husc4.HARVARD.EDU (mitsuharu hadeishi)
Newsgroups: comp.sys.amiga
Subject: Re: Taking Over
Message-ID: <2450@husc6.UUCP>
Date: Thu, 2-Jul-87 14:14:29 EDT
Article-I.D.: husc6.2450
Posted: Thu Jul  2 14:14:29 1987
Date-Received: Sat, 4-Jul-87 07:43:04 EDT
References: <3788@spool.WISC.EDU>
Sender: news@husc6.UUCP
Reply-To: hadeishi@husc4.UUCP (mitsuharu hadeishi)
Distribution: comp
Organization: Harvard Univ. Science Center
Lines: 22
Summary: There are various levels of this, depending on what you need

In article <3788@spool.WISC.EDU> derek@speedy.WISC.EDU (Derek Zahn) writes:
>A question.  What is the procedure for "taking over the machine" from the
>workbench (so the program can be guaranteed all the resources) and then
>giving it back when finished?

	Well, if you just want to make sure no other program steps on
anything (like screen structures, etc.) while you are modifying them,
then you have to do a Forbid()/Permit() which guarantees that you will
be the only task running.  This does not stop interrupts, however, which
you typically would not want to stop anyway.  These periods should be
SHORT, VERY SHORT, and should be used sparingly.  The only way to
guarantee access to all resources is to hardwire your program to take
over the machine at boot time, because if it is started later some other
task might have taken over some other resources (like the serial port, etc.)
before you started.  What kind of resources do you want to be "guaranteed"?
You realize the Amiga has a resource arbitration scheme so if another
task is using a resource you cannot have access to it?  In that case your
program should simply wait for the resource or die.  I really don't see
much use in taking over the machine unless you are a VERY processor-
intensive game program or something that needs all the sprites, etc.

				-Mitsu