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

 

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

 

Hallo Wolfgang -
I can help you if you willing to pay for it. Please respond to my private
email address 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

Wolfgang Busch schrieb in Nachricht ...