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From: hans@umd5.umd.edu (Hans Breitenlohner)
Newsgroups: comp.sys.atari.8bit
Subject: Re: What's the right way...
Message-ID: <2005@umd5.umd.edu>
Date: Thu, 22-Oct-87 15:30:50 EST
Article-I.D.: umd5.2005
Posted: Thu Oct 22 15:30:50 1987
Date-Received: Sun, 25-Oct-87 08:51:18 EST
References: <871006122252.4.JRD@GRACKLE.SCRC.Symbolics.COM>
Reply-To: hans@umd5 (Hans Breitenlohner)
Organization: University of Maryland, College Park
Lines: 28

In article <871006122252.4.JRD@GRACKLE.SCRC.Symbolics.COM> jrd@STONY-BROOK.SCRC.SYMBOLICS.COM (John R. Dunning) writes:
>What's the right way
>to return from a program to DOS?  I always thought the protocol was that
>DOS (any DOS) effectively JSR'ed to the start address of the program
>once it was loaded; thus the right way to return was just to RTS.
>That's always worked for me, using DOS XL.  However, I've gotten some
>reports that Kermit-65 sometimes wedges up when one exits from it.  I'm
>pretty sure I'm not trashing the stack; it really looks like DOS expects
>something other than an RTS.
>


While your way should work usually, here is a different way.  This is what
Turbo-Basic does before returning to DOS:

1. Clear locations $D200-$D207 (audio registers)
2. Close IOCBs 1-7
3. Jump indirect through DOSVEC ($000A).

If you have done interesting things with the screen, it might be even better
to refine step 2:
 
2a: Close all IOCBs.
2b: Open IOCB 0 for screen editor.

Of course you can skip step 1 if you have not done anything with the
audio registers, and it may be that DOS (some DOS) will do the equivalent
of steps 2a and 2b after you return.