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https://github.com/tinue/calc-u-59

Emulator / debugger for the TI-59 calculator platform.
https://github.com/tinue/calc-u-59

debugger emulator instruments texas ti-58 ti-58c ti-59

Last synced: about 2 months ago
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Emulator / debugger for the TI-59 calculator platform.

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README 

          
# Calc-U-59



A TI-59 hardware emulator and integrated debugger for macOS, built for researchers and enthusiasts who want to understand the machine rather than merely use it.



## Purpose



Calc-U-59 is a research tool, not a calculator replacement. While it accurately emulates the TI-59's processor (the TMC0501), its primary audience is people who want to explore how the TI-59 works: stepping through ROM code, inspecting registers, tracing printer output, loading raw machine-state files, and understanding the quirks of the original hardware.



A second audience is people who have found their own old TI-59 programs — whether on magnetic cards, in printed listings, or from memory — and want to revive them: run them again, understand what they actually do at the machine level, or improve them with the benefit of a full debugger.



If you are looking for a polished calculator app, this is probably not for you. If you want to run programs under a debugger, observe how the ROM handles edge cases, or reproduce behavior from original hardware, you are in the right place.



## Features



- Cycle-accurate TMC0501 CPU emulation

- Integrated debugger with register inspection and program memory dump

- [Debug GUI](docs/USERGUIDE.md) — three-tab debug panel (LIVE, CPU, LOG) with live register view, CPU inspector, and ROM overlay execution (ASM overlay controls are in the CPU tab)

- [Debug API](docs/DebugAPI.md) for scripted access to CPU state, breakpoints, instruction tracing, and disassembly

- Printer trace mode (functional simulation — see limitation below)

- `.ti59` state file format for loading calculator state

- Card reader emulation



## Current Limitations



**Printer:** The PC-100C thermal printer is not hardware-emulated. The printer output is simulated functionally: the emulator intercepts the ROM's print commands and renders characters using a pixel-accurate dot-matrix font calibrated against physical hardware, but does not model the actual printer interface timing or mechanics. It will not reproduce timing-sensitive printer interactions.



**Debug API:** Despite being a research tool, the debug API is still in its infancy. Live view and inspection, step by step

operation of both calculator-level and CPU-level instructions work. Still missing are breakpoints, keypress latch while

single stepping, or any sort of dynamic freeze (e.g. on register change). The API surface will change as it matures.



**Library module:** The Master Library module is hardcoded. Switching to a different Solid State Library module is not yet supported.



**Build:** Xcode only (macOS and iOS/iPadOS). No standalone build or cross-platform support yet.



**Building from source:** The project contains your Apple Developer Team ID and bundle identifier (`ch.erzberger.calcu59`). To build it yourself, open the project in Xcode, go to the target's *Signing & Capabilities* tab, and change the team to your own Apple Developer account — Xcode will update the bundle identifier automatically. To run in the Simulator no changes are needed at all. If you want iCloud (card file syncing) to work on a real device, you also need to register a new iCloud container in your Apple Developer account and update the two container identifier strings in `Calc-U-59.entitlements` to match.



## macOS Installation



A pre-built, notarized macOS DMG is available on the [Releases page](../../releases) of this repository.



**Install:**



1. Download the `.dmg` file from the latest release.

2. Open it and drag **Calc-U-59.app** into your Applications folder.

3. Eject the disk image.



**First launch:**



Because Calc-U-59 is distributed outside the Mac App Store, macOS will show a security prompt the first time you open it — even though the app is notarized by Apple. Double-clicking the app will produce a message saying it cannot be opened.



To open it the first time, right-click (or Control-click) the app icon and choose **Open** from the context menu. macOS will ask for confirmation once; after that, the app opens normally with a double-click.



Alternatively, you can go to **System Settings → Privacy & Security**, scroll down to the security section, and click **Open Anyway** next to the Calc-U-59 entry.



## iPhone and iPad



### Installation



There is no App Store version of Calc-U-59 for iPhone or iPad, and there may never be one. Apple's App Store regulations around emulators are strict and subject to change, so distribution through that channel is uncertain. For now, the only way to run Calc-U-59 on an iPhone or iPad is to build it yourself from source using Xcode and install it on your device directly (via a developer account or free provisioning profile, subject to Apple's usual limits on sideloaded apps).



### iPad layout



The iPad adapts its layout based on orientation:



- **Landscape:** The layout mirrors the Mac experience — the calculator, printer tape, and debug panel are shown side by side.

- **Portrait:** The layout matches the iPhone, with the printer accessible via navigation buttons (see below).



### iPhone layout



On iPhone (and iPad in portrait), only one panel is visible at a time. The calculator is shown by default. A chevron button in the top-right corner of the calculator switches to the printer tape view; a chevron button in the top-left of the printer view returns to the calculator.



The debug panel is not available on iPhone.



## AI Programming Assistant



The file [`prompt/ti59-agent-prompt.md`](prompt/ti59-agent-prompt.md) is a system prompt that turns a capable LLM (Claude, GPT-4o, etc.) into a TI-59 expert. Paste the entire file as the system prompt, then ask the model to write, explain, or debug TI-59 programs. It outputs ready-to-load `.ti59` state files.



**What it covers:** complete key-code encoding, all instructions (conditionals, DSZ, flags, indirect addressing, subroutines), the AOS operator-precedence system, alphanumeric printing via Op 00–06, the full PC-100C character table, and `.ti59` file format rules including when to use preset registers.



**How to use it:**



1. Open your LLM interface and set `prompt/ti59-agent-prompt.md` as the system prompt.

2. Ask for a program in plain language, e.g. *"Write a program that sums 1 to N"* or *"Print a sine table from 0° to 90° in 5° steps"*.

3. The model returns a `.ti59` file. Save it and load it in the emulator.



**Token cost:** The prompt is large (~15 000 tokens). Every conversation turn carries this overhead. Use a model with a generous context window and be aware that costs add up quickly in long sessions.



## Changelog



See [CHANGELOG.md](CHANGELOG.md) for version history and release notes.



## License



Copyright © Martin Erzberger. Licensed under the [Polyform Noncommercial License 1.0.0](LICENSE).



Free to use, modify, and redistribute — including to build ports for other platforms (Android, Windows, etc.) — for any noncommercial purpose. Commercial use requires separate written permission from the author.



## Acknowledgements



Special thanks to:



- **hrastprogrammer** ([hrastprogrammer.com](https://www.hrastprogrammer.com)) for the first emulator core that made this work possible.

- **Hynek Sladký** ([hsl.wz.cz/ti_59.htm](https://hsl.wz.cz/ti_59.htm) — currently offline, [archived 2024-08-18](https://web.archive.org/web/20240818211248/https://hsl.wz.cz/ti_59.htm)) for the initial ROM dump of the TI-59.