A couple of novice questions

[Frederic Breitwieser]

>>1) Is a modified ECM EPROM a violation of copyright? I know changing
>>the maps (data) might not be a violation, but I'd also have to carry a copy
>>of the original microprocessor code too. Is this in the public domain or
>>is it just something no OEM bothers to enforce?

According to a good friend of mine, who is a laywer, responded with the
following:

"If the common materials that arrive with the vehicle when sold, does not
prohibit or legally interfere with one's desire to edit, modify, or change
code within the ECM, then its legal.  The code within the ECM at time of
manufacture is owned by the manufacturer and subject to intellectual
property laws."

Then he smiled, inquring who'd want to sell the OEM chips other than the OEM ?

>>2) Would it be possible to use a larger size EPROM and wire up some kind
>>of switch so I could hold the original maps and code, and a copy of the
>>modified maps in the upper area. Switching from one bank to the other (with
>>the ECM unplugged of course). This way I could do semi-live comparisons or
>>revert back to the original maps if needed.

Most of the GM ECMs have their eeproms in sockets, therefore, you could
make a bank switcher, however realize the maps and code are in the same
chip, therefore your code needs to be identical (or at least jump to the
same places), thus preventing an ECM from switching to a different set of
code in the middle of an instruction read.  Devices exist, I've seen them
installed in various Grand Nationals (you know, that black rocket-like
Regal from the mid-80's?).  Anyway, if the code is the same, but the maps
are different, switching mid-stream shouldn't be an issue, though you might
experience a hiccup if the maps are radically different.


Frederic Breitwieser
Bridgeport, CT 06606
http://www.xephic.dynip.com/

1993 Supercharged Lincoln Continental
1989 4-Door Softtop Humvee (Hummer)
2000 Buick GTP (Mid-engine track car)

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