Error at 7FFE

[Ludis Langens]

Tim Ganger wrote:
> 
> Thus if 7FFE was changed to 00 the resulting address the prosser would jump
> to would be 0000 which I belive is the static
> RAM aera of the mem map. Then the SES light would flash and the engine run
> like do-do because the prosser would not have any usable data to work
> with.

The SES light won't blink on it's own.

The corrupt reset vector will send the CPU off to never-never land -
leaving the SES light in the power-on reset state.  The watchdog timer
will fire about 1/32 of a second later.  This will reset the CPU. 
Because a different vector is used for this reset, the ECM should start
booting normally.  At this point, it should compute a bad ROM sumcheck. 
Software might then blink the SES light.  Or, it may intentionally reset
the CPU, blinking the SES light as a side affect.

Anyway, all during this time, the engine should be running in limp-home
mode.  Hence, the poor running.

-- 
Ludis Langens                               ludis (at) cruzers (dot) com
Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/