[Gmecm] disassembly 101 / writing a commented hack

[William Lucke]

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