RPN83P: RPN calculator for TI-83+ TI-84+ inspired by HP-42S

[bxparks]

(12-03-2023 09:37 AM)jthole Wrote:  About keystroke programming; I agree that it wouldn't be really needed on the TI-8x Plus, since it already supports TI-Basic. But it would be really nice if I could XEQ a Basic program from within the RPN app. However, I understand that might be challenging to implement.

To be honest, I know very little about TI-BASIC, having written only 3-4 TI-BASIC programs in my life. I guess you are looking to run a BASIC program that can read and update the REGS and STK variables used by RPN83P? It's an interesting idea, but it feels like a LOT of work. If someone who knows the TI-OS better than me wants to explore that, and eventually sends me a PR, I would be willing to take a look.

Off the top of my head, I can think of some major obstacles or features that need to be addressed:

* A program/file browser: The user needs to be able to view, select, and execute the BASIC program from the RPN83P program. No idea how easy or hard this would be.
* Handling archived programs: A BASIC program can be "archived" into flash memory. Normally, TI-OS forces you to "unarchive" the program to RAM before it can be executed. There are "shells" that have gotten around that and allow launching programs from flash directly, but that level of TI-OS manipulation is beyond my technical expertise.

(12-03-2023 09:37 AM)jthole Wrote:  I would love keystroke programming and a solver, but that is probably way more work than being able to call Basic programs. If I understand correctly, the register list variable can be manipulated from within a Basic program, so that these register values are available within the RPN app (would work both ways).

Me too, I would love to implement the keystroke programming feature. The interesting thing is that I already have a pretty good idea how to implement this. I can already see the code in my head: I know how I would write the parser, how to write the interpreter loop, how to encode the data structures, and so on. The problem is that all that code in my head is in C or C++. From my coding experience so far on this project, I don't know if I can implement all that in Z80 assembly language before I start losing my mind.

The Solver is another feature that I would love to implement, but I think it is a tough problem. The algorithms used by HP, even in their earliest HP-34C calculator, are so advanced, I don't know if I have the mathematical and programming skills to create something that would satisfy an HP calculator user.