Path: utzoo!mnetor!uunet!cbmvax!steveb
From: steveb@cbmvax.UUCP (Steve Beats)
Newsgroups: comp.sys.amiga
Subject: Re: Boot blocks and such
Message-ID: <3181@cbmvax.UUCP>
Date: 22 Jan 88 16:12:00 GMT
References: <2390@crash.cts.com>
Reply-To: steveb@cbmvax.UUCP (Steve Beats)
Organization: Commodore Technology, West Chester, PA
Lines: 27

In article <2390@crash.cts.com> steelie@pro-charlotte.cts.com (Jim Howard) writes:
>What would be the procedure to place for example an 8k compiled
>program in the boot block on the amiga disk?   No, this isnt for
>writing a virus or anything, I just would like to know the procedure

You can't put an 8K program onto a 1K boot block.  The system bootstrap s/w
in the Amiga only reads the first 2 sectors off a floppy before calling it
for execution (if the checksum is OK, see other postings on this subject).
My suggestion is that the code in your custom boot block reads another 16
sectors into memory and executes those before returning to the strap code.

However, here's the rub, if a game autoboots via the startup-sequence then
you can just run NoFastMem before the game, right?  If a game autoboots by
putting custom code in the boot block, chances are it checks this code for
protection purposes too.  You go altering it and your game ain't gonna go!

Oh yeah!  I just thought about something else too.  You said a 'compiled'
program.  That means you're going to have to do all the relocation stuff
because a compiled program is pretty darned sure to be position dependent.
In addition to this, it is probably expecting DOS to be up and running (which
it isn't this early in the boot sequence) and will want things like default
input and output streams.  The only 'simple' way to get this working is
with position independent assembler.

In short; it ain't so simple.

	Steve