help needed for patching 89C51RD2 HEX File

Hi everybody,

we need to patch some bytes of a 89C51RD2 Atmel HEX File.

(we need to change some Values but do not have anymore the sourcecode and the developing equipment because our developer stopped working for us)

We tryed it with a Hex-Editor which do the checksum calculation but after that the controler does not work.

So we think, that there must be somewhere else some checksum or so, but we tryed disassembler etc. no chance.

any idea what we can check else? or someone here who would like to help us?

Thanks,

Wolfgang

Reply to
Wolfgang Busch
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I don't understand why you don't have the source code if it was developed for you or your company. If the company paid for its development, it should have the source code. Did the company not think that the source code was important, did the original programmer steal the source code, or did you lose it?

If it was developed on contract, I would contact the developer and either ask for him to make the change for a fee, or ask for a copy of the source code, which should have been provided.

It the developer was working as an employee, that probably won't work.

Does that mean that the program loaded without error? Can you verify that?

It is possible that the program itself does a checksum on the code to verify the integrity. If so, I expect that there would be some documented error response to that occurrence. It might just refuse to run at all, though.

What do you mean by "tryed disassembler etc. no chance"? Disassemblers work.

You may need to hire a professional to help you with this one.

Thad

Reply to
Thad Smith

Hallo Wolfgang - I can help you if you willing to pay for it. Please respond to my private email address otc snipped-for-privacy@gmx.net for further discussion. I'm a experienced disassembler for 8051, 68000 code. It should be no problem. (Possible to communicate in German language) Regards - Henry

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Reply to
Henry

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