[Diy_efi] if YOU were bored enough to disassemble...

[Andrew Brownsword]

I've spent a fair bit of time exploring the 32K ROM from my Ford Probe  
GT, which uses a Mazda MECS-II ECU that is based on a MC68HC11 variant.  
  I had quite a leg up from another PGT owner who had done quite a bit  
of hardware examination and poking around in the ROM.  It is hard work  
and difficult to be sure of what you find -- this isn't a task to be  
taken lightly!  I have spent most of my time in the fueling and load  
measurement logic since my intention is to upgrade the injectors and  
replace the airflow sensor with a MAF in order to be able to feed my  
aftermarket turbo.  The timing code is a whole other ball'o'wax.  I'm a  
software engineer professionally with a fair bit of assembler  
experience, so I had a good base of knowledge with which to start, and  
I wrote my own reverse-engineering oriented disassembler.

The Motorola website has lots of documentation for the HC11:

http://e-www.motorola.com/webapp/sps/library/ 
documentationlist.jsp?rootNodeId=01&nodeId=01M98635&Device=68HC11E0&DocT 
ype=Reference+Manual




On Wednesday, August 21, 2002, at 03:18 PM, Dave Gallant, 12 Point  
Racing wrote:

...
> I will start with the hardware. The ECU is a Weber 1.6M ECU using a  
> Motorola
> 68HC11 processor, with a 27C512 EPROM socketed on. I am told older  
> Fords
> (possibly cosworths?) used this very ECU to drive their applications,  
> so
> possibly someone has dealt with this ECU in the past. Things of  
> interest in
> the EPROM code are the fact that almost all BIN files I have collected  
> share
> the "3 part" design, with a base level code chunk, a separate code  
> chunk for
> the specific maps and calibrations, and a small starting code block  
> that
> dictates the memory starting point and I believe external hardware  
> links.
> ...


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