As far as toggling back and forth between computers - it'd be a lot more
complicated. The Chevy folks might be able to get away with a simple
multi-pole make-before-break switch for the computer's access to the ROM
chips (though this isn't likely to last very long - far better to do it
in logic and sync it with CPU reads). Switching between complete SBECs
would require that both units have constant access to the vehicle's
sensors (there's some history info involved), else you'd be running in
each computer's start-up open loop for a while after switching.
All in all, it'd be far easier (and more fun) to dump everything from
both sets of ROMs, reverse engineer the program, and re-implement them on
a laptop. Then you could tweak all sorts of parameters, add additional
capabilities... the possibilities are endless.
Any newer Pentium or PowerPC laptop would have plenty of horsepower to
replace the SBEC's CPU. You'd probably want to have a modified SBEC for
some of the analog circuitry, as well as buffers and interfaces to the
engine and sensors.
I'd love to do that kind of stuff for a living...
Jim
-- Happiness is (according to Aristotle): "The exercise of vital powers along lines of excellence in a life affording them scope."
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