Calc-U-59 is a TI-59, TI-58, and TI-58C emulator for iPhone, iPad, and Mac. It runs the original ROM, so every program, module, and quirk works exactly as it did on the real hardware — with virtual magnetic cards, a PC-100C printer, all fourteen Solid State Software modules, and a CPU-level debugger for anyone who wants to look under the hood.
CYCLE-ACCURATE EMULATION
The TMC0501 processor is emulated at the cycle level, reproducing the exact behaviour of the original hardware — including the TI-58C's constant memory, preserved across restarts. The Master Library ROM and many more modules are included.
INTEGRATED DEBUGGER
Inspect program memory, data registers, CPU state, and internal SCOM registers live as the machine runs. Step through instructions one at a time, or let the emulator run and freeze it at any point. You can even run your own assembly programs! On iPad in landscape and on the Mac it sits beside the calculator; on iPhone and in portrait, turn on the debugger page in Settings.
PAPER TAPE PRINTER
A functional recreation of the PC-100C thermal printer with dot-matrix font rendering. Trace exactly what programs print and why. Copy output as plain text or as a high-resolution bitmap.
MAGNETIC CARD READER
Load and save programs and data registers as card files, stored on your device and synced via iCloud. Bring old listings back to life and run them under the debugger.
STATE FILES
Load .ti59 and .ti58(c) state files to instantly configure the machine with a program, registers, and flags — ideal for sharing reproducible scenarios or revisiting known machine states.
SOLID STATE MODULES
Select a Solid State Module and run programs from there.
Whether you're bringing an old program back to life, running the Master Library modules, or exploring how these machines actually worked under the hood, Calc-U-59 gives you a faithful TI-59 in your pocket.
Calc-U-59 is free software under the GPLv3; the source code is on GitHub.
I saw a reference to this app on Facebook and, having owned a TI-59 with the printer I immediately downloaded it and began playing. It's an amazing program! I can't figure out how to add the function key labels to a program card — a help file would be quite, um, helpful.
• STATE FILES: "WaitFullSpeed:" is gone: it took effect only after the program had stopped. Put "FullSpeed:" before the key that starts the program instead; the bundled presets now do, and the long ones finish at full speed. An unknown KEYSTROKES directive or a "Wait:" without a unit is now reported as an error instead of being read as keys.
• TI-58C: Runs at a real TI-58C's speed, measured on a unit: about 2.6% faster than before. Its error blink takes 0.91 s stand-alone and 0.71 s on the PC-100C, as on the real calculator.
• PRINTER: Prints at the real PC-100's speed, measured on a TI-59 and a TI-58C: a printed line takes about 0.29 s on the TI-59 (a List line 0.31 s, was 0.21 s), a blank line from Adv about 0.19 s (was 0.40 s). The printer runs on the calculator's clock, so on the slower TI-58C everything prints 15% slower, as on the real one.
• PRINTER: The printer interrupt now cuts a line the way the real printer does: the row it interrupts keeps the dot columns already fired (right to left), and a dot cut early in its heating comes out faint. Measured on a TI-58C and a TI-59 with a PC-100A.
• EXAMPLES: "calendar-09-dispatch.ti59" prints a year 1.8 s faster: 75 s for 2026, 7% faster than Acosta's 1981 program.
FIXES
• STATE FILES: A "PARTITION:" too large for the calculator now aborts a "SKIP-RESET" load too, as it already did a normal load.
• STATE FILES: A file with "SKIP-RESET" and a "PROGRAM:" no longer clears the data registers: "fast-grafik-3d-plot-part2.ti59" plots again with the values entered in part 1, instead of stopping at once with "1.".
• DEBUGGER: The CPU tab no longer stands still during the TI-58's error blink, when the calculator runs the same short loop over and over.
Version 2.1.0
The developer, Martin Erzberger, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Privacy practices may vary, for example, based on the features you use or your age. Learn More
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
