Calc-U 59 — TI-59 emulator app icon
Calc-U 59User Guide

TI-59 emulator for Mac, iPhone and iPad

Calc-U 59

Calc-U 59 is a TI-59, TI-58 and TI-58C emulator for macOS, iPhone and iPad. It runs the original Texas Instruments ROM, reads and writes virtual magnetic cards, emulates the PC-100C printer and all fourteen Solid State Software modules, and includes a CPU-level debugger. You can try it in your browser before you install anything.

The Calc-U 59 TI-59 emulator running on an iPhone, showing the red LED display, the cue card and the full key matrix

iPhone and iPad

Install from the App Store, then open the app and pick a model. State files load from the file picker inside the app.

Mac

Download the release from GitHub, drag the app to Applications, then use right-click Open the first time if macOS blocks it.

Where to start

01Setup

Installing on iPhone and iPad

The App Store install path, plus what happens on first launch.
02Setup

Installing on Mac

GitHub Releases, the DMG, and Gatekeeper the first time you open the app.
03Files

Loading a state file

What a .ti59 file contains and how the parser treats each section.
04Debug

Using the debugger

CALCULATOR, CPU, LOG, freeze/step, and the binary trace file.
05Hardware

Printer and card reader

What the PC-100C panel does and how card files are managed.
06Help

FAQ

Answers to the questions users actually hit first.

What Calc-U 59 emulates

Calc-U 59 emulates the TI Programmable 59 that Texas Instruments introduced in 1977, along with its two smaller siblings, the TI-58 and the constant-memory TI-58C. It is not a reimplementation of the maths in Swift: the app runs the calculators' original ROM through an emulated TMC0501 processor, so AOS precedence, the 13-digit internal precision, the flashing overflow display and the documented quirks all behave the way the hardware did.

  • Switchable TI-59 / TI-58 / TI-58C models, with the correct memory partition and startup state for each.
  • All fourteen Solid State Software library modules, from the Master Library to the RPN Simulator — see the full list.
  • Magnetic cards read and written as files, synced between your devices over iCloud.
  • The PC-100C thermal printer, in both a dot-matrix view and a copyable text view.
  • A CPU-level debugger with a live program listing, a ROM instruction trace, and binary trace capture for offline analysis.
  • Plain-text .ti59 state files that carry a program, the registers, a cue card and a module selection in one readable file.

New to these machines, or trying to work out which model you owned? Start with the background on the TI-59 and TI-58 →

Available now

The Mac build ships free from GitHub Releases. The iPhone and iPad build is on the App Store. The source code is on GitHub.