GM Code Location

[Joe Boucher]

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