GM code location

[Robert W. Hughes]

Save your energy hunting for 6809 stuff. It is a Motorola chip but the
early GM computers use a 6801 derivative. They are more or less
compatible at the source code level but differ internally. The 6801 is a
6800 with extra on-chip resources and a few added instructions. The
68HC11 is more of the same.

On the subject of prom image files and checksums, if the file is in S19
format (each line starts with S1) there is a checksum at the end of each
line. If a line is edited this checksum must be corrected or the PROM
programmer will not accept it. Hex and binary formats contain just the
data and hex format is much easier to edit. 

There is also a checksum in the prom image. If any changes are made this
checksum must be corrected or the car will not run. The check engine
light will just flash rapidly when the ignition is turned on.
-- 
Robert W. Hughes (Bob)
BackYard Engineering
Houston, Texas
rwhughe at hal-pc.org