Re: 6809 / 6702 puzzle

From: Rhialto <>
Date: Thu, 12 Apr 2012 02:01:34 +0200
Message-ID: <>
On Wed 11 Apr 2012 at 14:56:23 -0700, Mike Naberezny wrote:
> Do you know enough about the 6702 checks now to modify the original
> binaries to bypass them?

I think that most of the pieces have been posted in this thread.

Dave posted a list of all start addresses of the check routines in the
various binaries.
I posted a disassembly of the check routine, and (not to forget), the
routine that checks the check-routine. Both would need to be patched
out: the first certainly returns with D=0000 (and appropriate flags),
and the second most likely too. I never tried to trace where they're
being called from and stub them there.

I don't know how the load module format differs from the in-memory
format though. The check routine isn't position-independent, since it
contains a small data table and a reference to it. The check-check-
routine contains a reference to the check-routine, and a final
adjustment to the checksum that likely differs in each binary (because
the table reference in the check-routine differs in each).

___ Olaf 'Rhialto' Seibert  -- There's no point being grown-up if you 
\X/ rhialto/at/    -- can't be childish sometimes. -The 4th Doctor

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Received on 2012-04-12 01:00:05

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