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TI-57 emulator beta testers needed ... [OT] - Printable Version

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TI-57 emulator beta testers needed ... [OT] - HrastProgrammer - 12-28-2005

As some of you already know, I am investigating a possibility to develop a TI-59 emulator for HP-48GX/49G for some time. While such emulator is still very far away, I just succeeded to make a true TI-57 emulator for Windows (TI-57E). Although I am with HP most of the time, TI-57 was my first (programmable) calculator so it has a special value for me because I learned (calculator) programming on it.

To be honest, TI-57E is more a development and test platform because it is very ugly but it does the job. The development was possible because of the availability of a few TI patents describing TMC1501 CPU and containing TI-57 ROM object code. This object code was obviously manually retyped on a typewriter because it contains a lot of errors. And each patent has different errors so I took 6 of them and compared the whole ROM instruction by instruction (I just had nothing smarter to do during the holydays) trying to figure out which instruction is correct if there is a difference between individual patents. Then I wrote a disassembler and disassembled the ROM and resolved a few more errors by running the emulator and following the instruction traces. Currently there are just a few instructions for which I am not 100% sure but it seems like they are all correct. The additional problem was that this object code is probably not from the final product because it contains a few bugs which aren't present in the production calculators (or, at least, I haven't heard about them): (1) RST instruction breaks a running program and (2) Sigma+/Sigma- corrupt instructions at program steps 48 and 49 (and modify program counter, as well). I corrected these bugs so TI-57E seems to work correctly for all test cases and programs I executed. Even synthetic programming is working so CPU emulation is complete. For example, the famous GTO 2nd 48 LRN Exc SST Lbl 1 GTO 2nd 48 R/S INV STO 3 +/- +/- sequence which in fact turns TI-57 into TI-57C is working (and from the ROM disassembly I can even find why)!

As far as I know, it is the first real emulator of an old TI calculator and TMC CPU ever. The second stage would be to port TI-57E to HP-48/49. But, before I proceed, I need a few beta testers for TI-57E. If you are interested then you can contact me by mail (e-mail address is somewhere on http://hrastprogrammer.tripod.com) ...

Thanks and sorry for OT ...


Re: TI-57 emulator beta testers needed ... [OT] - Vieira, Luiz C. (Brazil) - 12-28-2005

Hi, Hrast;

I still have my TI57 (working fine, and effectively my first calculator...), and I can go ahead trying out whatever you want related to it. I am sure that there are many other owners around here, so, consider me as one of them.

lcvieira (at) quantica (dot) com (dot) br

As you know, I have the HP49G/G+ and the HP48SX/G+/GII And I'd gladly try your emulator out.

Best regards.

Luiz (Brazil)


Re: TI-57 emulator beta testers needed ... [OT] - HrastProgrammer - 12-29-2005

I forgot to mention (in all mails) that you can access the debugger and look at the CPU registers by double clicking with the mouse on the emulated display above the keyboard ...