Checksum

[Roger Heflin]

> POWERCHIPS- A Força Virtual para seu Carro wrote:
> 
> What I am needing same and a software that makes I calculate automatico of
> checksum for flash eprom 29F400 and 29F800 in unit of command of electronic
> injection. I bought a software of tunercat in the site:
> http://www.tunercat.com/tnr_desc/do_tc.html
> But this software only makes calculates of checksum in eprom 27C128,27C256 for GM and
> FORD
> and others. But this software does not calculate checksum for flash eproms
> as mentioned above. Do you possesss some software similar that makes
> calculates of checksum automatico for this flash eproms?
> Sincery;
> Anilton Santos.

The checksum is not defined by the eprom/eeprom used, the checksum is 
defined by what is on the chip.   All of the GM checksums are defined
by the GM software running on the chip, and have nothing to do with
the chip.    So GM's definition of a checksum is very likely different
from Fords definition of a checksum, even if they use the same chip.

And whatever car computer that you have will be most likely be different
unless it is a variant of one of the above.

And odds are if you don't know how the checksum is calculated for 
the chip you are working on, you probably also don't know enough
to reprogram it in any useful manner.

The problem is not nearly as simple as you seem to think.

			Roger
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