Solver and Integrator: Program questions

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ijabbott
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Re: Solver and Integrator: Program questions

Post by ijabbott »

Thomas Okken wrote:
Thu Jul 04, 2019 3:46 pm
Walter wrote:
Thu Jul 04, 2019 3:11 pm
Thomas Okken wrote:
Thu Jul 04, 2019 6:56 am
With something like a solver, the algorithm is everything. Whether you code it in assembly language, SysRPL, or C, is just an implementation detail.

I bet the HP Solve algorithm has evolved since the 34C. It would be interesting to see the commented source code for the various implementations over the years, if they still exist, and if HP ever choose to open-source them...
This would be something really worth of re-engineering. Since one can do a ROM dump of the HP-42S, wouldn't it be possible to decode it? Presumably too much work... (though by comparison to the HP-15C ROM, one may find similar structures. Matching patterns?). Probably I am showing up as having absolutely no idea of such a task...
It's possible, but a lot of work. Back in the early '80s, a friend and I spent some time analyzing the ROM of his Commodore PET, and we encountered quite a few spots where we just couldn't figure out what was going on. We gave up after a while. I'm sure I'd do better now, but then again, the HP-42S has a lot more ROM than the PET, and Saturn assembly language is harder to read than 6502. Still, it could be done, and HP Solve reverse-engineered that way, but it seems like a waste of time, since you wouldn't be able to use the results of that work anyway. Any re-implementation of HP Solve would be considered a translation, and still covered by the copyright on the original code.
Copyright wouldn't come into it if it was a "clean room" reverse engineering project (cf. IBM PC clone BIOS). There may have been software patents, but they would have expired by now.
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