Path: utzoo!mnetor!uunet!tektronix!sequent!mntgfx!dclemans
From: dclemans@mntgfx.mentor.com (Dave Clemans)
Newsgroups: comp.sys.atari.st
Subject: Re: <Control> C and autostarting GEM programs
Message-ID: <1988Feb3.080736.14303@mntgfx.mentor.com>
Date: 3 Feb 88 16:07:34 GMT
References: <880201194539737.AETG@Mars.UCC.UMass.EDU>
Organization: Mentor Graphics Corporation, Beaverton Oregon
Lines: 20

Re: Control C

GEMDOS doesn't directly terminate a process when it sees a Control-C character
in a "cooked" input function; instead it calls a special pseudo-interrupt
vector called the critical exception handler.  The default code for that
handler is what terminates the process.  If you install a replacement for it
you can do whatever you want.  If I remember correctly this is described
in the Atari GEMDOS Users Guide manual.

Re: autostarting GEM programs

My understanding is that what the autostart programs do is to set up a
small TSR routine attached to the vertical blank interrupt vector.  On each
interrupt the code looks around and tries to guess whether or not GEM is
initialized yet.  If it looks initialized it disengages from the vertical
blank interrupt and starts the requested GEM program.  Whether or not a
specific version of this technique works with all versions of the ROM's
depends on specifically how the code checks for GEM being initialized.

dgc