[Gmecm] disassembly 101 / writing a commented hack

[Darren Freed]

That is the disassembler I used for all my 6811 needs.  It works well, 
and a text editor (with a good search function) is valuable to comment 
all the ram/rom locations as you figure them out.  There should be a 
definition file for your ALDL stream in that .zip file on the ftp site 
(I can't remember the name of the top of my head...).

I now use IDA, simply because a text disassembly of 332 based code is 
way to large/cumbersome to manipulate.

darren



William Lucke wrote:
> 
> No I do not have that disassmbler. Is this the correct page to get it: 
> http://dewhisna.home.netcom.com/download.html ?
> 
> I've heard of IDA... I guess I need to get Tunercat's as well and see 
> which one I like.
> 
> I don't know if there is a data definition for the ALDL stream. I would 
> assume so... I don't know about the stock chips, but my modified 
> engine-management-only program refuses to talk to a tech1. It ONLY talks 
> to the Cadillac IPC.
> 
> What's the definition of a P4 ECM? What are the other types? What 
> distinguishes them from each other?
> 
> Thanks
> 
> 
> Will
> 
> 
> 
>> From: davesnothereman at netscape.net
>> Subject: Re: [Gmecm] disassembly 101 / writing a commented hack
>>
>> I use Donald Whisnant's (spelling?) code seeking disassembler.  It's 
>> freeware written to disassemble code from GMECM's.  Tunercat also has 
>> one, but I'm not as familiar with it.  IDA Pro is also good, but not 
>> so free.
>>
>> Is there a data definition file for the norstar ALDL stream?  That 
>> would at least provide the correct order to the ALDL data words if you 
>> can find the ALDL xmit table.
>>
>> Most of the ALDL tables I've looked at begin with the prom id byte 
>> located in the beginning of the calibration.  If you know or can work 
>> out the calibration address then you might be able to make a guess at 
>> the beginning of the ALDL table.
>>
>> You're famaliar with the reset vectors located at the end of Motorola 
>> code... use those to separate code from cal. data.
>>
>> If you're working with a P4 ecm, look for hardware addresses in the 
>> 3XXX range and attempt to use those with known calibrations from other 
>> P4's to locate specific portions of code.  Use pattern matching to 
>> attempt to locate and  identify some common routines such as spark 
>> timing calculation.
>>
>> There's probably people much better at this than I am who can offer 
>> better clues.  But will they?
>>
>> Zaphod
>>
>> -----Original Message-----
>> From: William Lucke <william.lucke at highspeedlink.net>
>> To: gmecm at diy-efi.org
>> Sent: Sun, 14 May 2006 14:53:22 -0400
>> Subject: [Gmecm] disassembly 101 / writing a commented hack
>>
>>    I'd like to get started hacking the OBDI Cadillac Northstar 
>> computer (). I have a couple of different BCC's, as well as a dyno 
>> program that only has engine management turned on.
>>
>>   I'm familiar with assembly and have worked with commercial 68HC11's 
>> in development boards. I'm familiar with the concepts of disassembly 
>> and I'm ready to devote the time necessary to reverse engineer this 
>> program.
>>
>>  What I'm not sure of, however, is where to start.
>>  What's the best disassembler to use on GM chip images?
>>
>>   Is there a listing of the memory locations of the data for the ALDL 
>> stream? Other than starting at the beginning, I'm not entirely sure 
>> how to enter the program and know what's what.
>>
>>
>>  Will
> 
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