OEM EFI computers

[Lfaustini at aol.com]

In a message dated 95-05-31 10:18:52 EDT, you write:
> There are also masked roms in the OEM ECM's (at least GM.. Don't know about
> others) That also control what it can and cannot do.  The replaceable Eprom
> of a GM (Chryslers are sealed and potted) contains the program (firmware)
> and look-up tables that control the individual functions... Also, just by
> changing 2 chips in a GM.. The Calpack and the Eprom, it can be used on a
> variety of engines.  If interested, I have a 32k file of the Eprom of a
1987
> buick GN (turbo 3.8l V6) disassembled I can send you to examine... They use
> the 6801.
> Later,
> Dave

    I looked at the GM computer system very extensively. (1992 5.7 TBI moel)
That computer uses a 68hc11FN. Nice chip. All of the code resides on the
27256 in the calpack. Thats a 64k byte rom, and the cpu only has a 64k byte
adress space, so I am assuming that ALL of the code is on the calpack. Oh,
yeah, that version of the '11 has programable chip selects too. Anyway,  I
doubt that GM bothered with programing the on chip mask ROM when they had
that big EPROM to use.  I am wondering if the GNX really used the 6801, or if
it was really a 6811. Anyone know this for sure? I would guess that they used
the '11 on the GNX, because its the first production car that GM ever
implimented SEFI on. The coding of a 6801 would be very dificult as compared
with the code required for the '11. The timer section of the '11 almost lends
itself to SEFI.  Oh, yeah, Can I get a copy of the GNX code? Is it
disasembled? Is it comented (yeah, right!) ?

    ---Lou