extratcingg preprogrammed 8051 chip with fuse locked

It is almost always cheaper to review the original specification, mails etc and recreate from that and a working unit than to fight with reverse-engineering. It also makes sure that the original source didn't contain a copyright clause that is reauired to have in the reverse-engineered source too doesn't result in inadvertent law violations. Remember that the compiler vendor may also forbid reverse-engineering of their runtime library. With a binary image, you don't know what instructions are from the runtime library and what instructions are from the application until a significant part of the application has been reverse-engineered.

A friend of mine had to do a full reverse-engineering of a project after a company spent a lot of money to have a consultant write some software for them. The consultant was a crook. He supplied a secretly time-limited binary image, and then demanded ransom for the contracted source - and finally ended up supplying the source (in return for a job position) to a competing, larger, company... The bad thing was of course that small companies can't afford the legal fees - especially if they have to fight a much bigger company.

It is almost always cheaper to review the original specification, mails etc and recreate from that and a working unit than to fight with reverse-engineering. It also makes sure that the original source didn't contain a copyright clause that is reauired to have in the reverse-engineered source too doesn't result in inadvertent law violations. Remember that the compiler vendor may also forbid reverse-engineering of their runtime library. With a binary image, you don't know what instructions are from the runtime library and what instructions are from the application until a significant part of the application has been reverse-engineered.

A friend of mine had to do a full reverse-engineering of a project after a company spent a lot of money to have a consultant write some software for them. The consultant was a crook. He supplied a secretly time-limited binary image, and then demanded ransom for the contracted source - and finally ended up supplying the source (in return for a job position) to a competing, larger, company... The bad thing was of course that small companies can't afford the legal fees - especially if they have to fight a much bigger company.

"It is almost always cheaper to review the original specification, mails etc and recreate from that and a working unit than to fight with reverse-engineering."

Absolutely!

I was just pointing out that it would - in principle, at least - be possible.
Whether it would be sensible or worthwhile is, of course, an entirely different question!

;-)

Yes, I saw the italics on the "entirely" :)

I just wanted to point out the non-obvious fact that it may be illegal to reverse-engineer your own project.

I once was tasked with recreating the code for a unit where the sourcde was lost (the factory burned and the i....s did not have off-site backup).
I spent a lot of time with a disassembly and then realized that recreating the code from scratch is far faster than deciphering a disassembly. This is even worse if the original is in C.

Erik

PS the chips were not locked the recereate was to add a feature.