Looking for a date for the gmecm eeprom

[Ludis Langens]

Dave Zug wrote:
> 
> >The vehicle speed limiter is hard coded in ROM, there is no changing it.
> 
> Would it not be possible to add a hardware modification, or even re-enable
> momentarily the 'write' enable on a OTP (if it IS an OTP) to alter the speed
> limiter in ROM? Even though memory 'bridges' are un-fused, you can still
> alter the 'ones' to be 'zeros' to make a different value.. this will RAISE
> the rom value, lowering it is only achievable by an involved hardware patch,
> or by replacing the ROM with your own version. Might be a bit excessive for
> what is achieved, but its neet to think about a solution.

If I remember the start of this thread, the ECM in question uses an
"almost everything in one" chip.  There is no seperate ROM chip.  In
fact, there is no processor bus available on the PCB.  All of this is
inside a single chip.  The chip gets analog sensor values input on one
side, and it outputs injector/ignition pulses on the other.  No
intermediate signals are available.

An earlier message said that most of the ROM/PROM memory is mask-ROM in
this chip.  That means that a layer of aluminum jumpers was masked down
onto the silicon chip to create the ROM image.  It isn't "changeable".

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


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