disassembly of 6803 code

[Christian Hack]

> Date: Tue, 05 Sep 2000 11:44:21 +0200
> From: Arnaud Westenberg <arnaud at casema.net>
> Subject: Re: disassembly of 6803 code
> 
> Peter Gargano wrote:
> > 
> > Arnaud Westenberg wrote:
> > 
> > > I have found a disassembler with support for the 6803 (DASMX) and
> > > disassembled it, it didn't complain. Do I have to check wether it has
> > > done its work properly?
> > 
> > Yes!
> > 
> > Disassembly is, to some extent, an interactive process. You won't get
> > a "good disassembly" until you know what the code is doing. Does DASMX
> > allow you to predefine labels for subsequent disassembly when you find
> > its first attempt was not so good?
> 
> I'm not sure, this is my first attempt disassembling stuff, would this
> be the "code threading" feature? Here's some information on the DASMX
> program http://show.silkera.net/~kphsu/software/prog/dasmx.html
> 
> Can I ever be sure wether I have the correct assembly source?
> 

I have personally used DasmX to disassemble the 6802 code from
my Nissan ECU. I then used Motorola's freeware assembler to put
it back together. Doing this I end up with an exact binary image
matching the original. I didn't have to manually hack the code 
after dissassembling either. It just goes straight into the assembler

The dasmx link you gave points to an out of date version. It's at
least up to 1.30 now. Try here:
http://www.softseek.com/Programming/Assembly_Language/Review_29643_index.html

Unfortunately it doesn't support predefined comments but it does
have tables, labels etc. Definitely use the code threading feature.
It works very well I have found. You just need to give it one or
two code entry points and it seems to find it's way through most
of the code. Since you know where the ROM lives in memory space
you should be able to give dasmx the reset/nmi etc vectors which
live at $FFFE, $FFFC etc. and that should be enough.

What brand is the ECU? If's a Hitachi or a Bosch I would be interested
in the bin file if possible. Where did you download the bin file from

Regards


Christian Hack
DESIGN ENGINEER
christianh at pdd.edmi.com.au
EDMI Product Development Division
Ph : +61 7 3881 6444
FAX : +61 7 3881 6420


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