GM Code Location

[Carl Summers]

Joe Boucher wrote:
> 
> My question is where is the code instructions for the 68mh11 chips used
> in the GM ECU's?  Is it stored by the eeprom chip or on the rom chip?
> Or someplace else?
> 
> I have pulled down some of the bin files off the diy-efi ftp site and
> with the help of a couple of kind hearted people, found a hex convertor
> and shown some table locations in a bin file.  My baseline understanding
> is that both the code to operate the processor and the lookup tables are
> both on the eeprom.  I understand there is a rom chip on the
> motherboard.  What's in that?
> 
> There are enough sparkies and computer types around here to help with
> some of the general questions.  But I would like to check one fact I was
> told.  I discoverd when looking at a raw hex file, the last two digits
> were not part of the code.  The mentor informed me it was a checksum for
> that line.  Here's the question.  If I change the value of a table, do I
> also have to manually change the checksum for that line and possible for
> the entire file?
> 
> Joe (ME in over his head) Boucher
> '70 RS/SS Camaro  '81 TBI Suburban

Joe,
  I have been told the 747 computer uses a 6809 processor, and the newer
stuff uses the 68hc11,,,I don't know this to be true,,,,what is this
68mh11 you were referring to and if it is the specific gm processor does
anyone have an assembly program for it????And,,,does anyone have an
assembly program for the 6809 processor,,,,any help is appreciated....
  As for checksums,,if you change anything in the lookup tables the
checksum for that has to be corrected and are in various spots depending
on the prom...as for the checksum for the code I don't know if there is
one but am hoping to understand how to unassemble the code soon..(btw
which is usually that huge lump of info at the end of the bin file,
although I have seen additions to the code in other places)
   If any of the code gurus on board would please lend a hand finding a
source to acquire the assembly stuff I would sure appreciate it..Thanks,
-Carl Summers
(snorkling about ten feet from the surface)