Calc-U-59

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.

QUIRKS
The calculator reproduces every quirk you've heard of: Fast mode, printer interrupt, display corruption — you name it.

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.