Article View: comp.sys.atari.st
Article #28236Re: TPA pointer
From: Allan Pratt
Date: Mon, 14 Sep 1987 18:03
Date: Mon, 14 Sep 1987 18:03
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1795 bytes
in article <3059@mtgzz.UUCP>, bds@mtgzz.UUCP (b.d.szablak) says:
> Using MONST I determined that the error was occurring because the value
> I was using for the TPA pointer (passed on top of the stack at startup)
> was 0L!
The basepage pointer is at 4(sp), not "the top of the stack" as you say.
This is so it can be taken as the argument to a C procedure like this:
_main(basepage)
long *basepage;
{
...
}
When the compiler compiles this, it expects that the return address from
the "JSR _main" is the long on top of the stack, and the arg is the SECOND
long on the stack (at 4(sp)).
As for the rest of your problem, I have to assume that it is a
misunderstanding between you, GEMDOS, and your debugger. OF COURSE
programs are being started at their entry points -- otherwise MONST
itself wouldn't work. But when you start the program with MONST, you
are introducing another player into the game. I haven't really played
with MONST, so I don't know how far to go with that theory.
/----------------------------------------------\
| Opinions expressed above do not necessarily | -- Allan Pratt, Atari Corp.
| reflect those of Atari Corp. or anyone else. | ...lll-lcc!atari!apratt
\----------------------------------------------/ "Yow! Am I interfaced yet?"
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: arc1-ca.pugleaf.net!utzoo!mnetor!uunet!husc6!mit-eddie!ll-xn!ames!amdcad!sun!imagen!atari!apratt From: apratt@atari.UUCP (Allan Pratt) Newsgroups: comp.sys.atari.st Subject: Re: TPA pointer Message-ID: <841@atari.UUCP> Date: Mon, 14-Sep-87 14:03:33 EDT Article-I.D.: atari.841 Posted: Mon Sep 14 14:03:33 1987 Date-Received: Thu, 17-Sep-87 02:35:01 EDT References: <3059@mtgzz.UUCP> Organization: Atari Corp., Sunnyvale CA Lines: 29