CEmu

CEmu is a free, open-source emulator for Texas Instruments' TI-84 Plus CE and TI-83 Premium CE graphing calculators, letting you run real calculator firmware and programs directly on your Mac without touching physical hardware.

What is CEmu?

CEmu is an open-source emulator that faithfully replicates the TI-84 Plus CE and TI-83 Premium CE calculators on desktop, including their eZ80 processor, USB connectivity, and color LCD. You feed it a real ROM image dumped from a physical calculator, and what you get back is a pixel-accurate, cycle-accurate recreation — fast enough for everyday programming and math work, detailed enough for debugging at the opcode level.

I keep CEmu pinned in my Dock during any TI-BASIC or Z80 assembly project. The speed alone justifies it: reset, flash new code, and see results in seconds rather than fumbling with the USB cable every iteration.

What does CEmu do best?

CEmu excels as a developer-oriented debugging environment — it is not just a calculator viewer but a proper toolchain companion. The built-in debugger surfaces the eZ80 register file, memory map, stack trace, and a disassembly pane side-by-side with the emulated screen. That combination is rare even among commercial emulators.

• Cycle-accurate eZ80 CPU emulation — your timing-sensitive assembly routines behave exactly as they would on real iron.
• Integrated debugger — set breakpoints, step through instructions, inspect RAM and flash regions live.
• ROM/state transfers — import and export calculator state; share a snapshot with a collaborator and they can reproduce your exact crash.
• Keyboard mapping — full Mac keyboard-to-keypad mapping so you never need a physical calculator for input.
• Speed control — throttle or crank the emulation speed for slow-motion debugging or rapid automated testing.

For educators writing curriculum programs or developers shipping games on Cemetech, CEmu eliminates the hardware dependency from the feedback loop entirely.

Is CEmu free?

Yes — CEmu is completely free and open-source, released under the GPL-3.0 license. You can download pre-built Mac binaries from the official GitHub releases page, or build from source yourself if you prefer. The one thing CEmu cannot distribute is the calculator ROM: you must obtain that legally by dumping your own physical device (the project documentation explains exactly how).

Who should use CEmu?

CEmu is built squarely for developers and students who write code for TI calculators rather than those who simply want to crunch a few integrals. If you are writing TI-BASIC programs, porting C code via the CE C/C++ toolchain, or crafting Z80 assembly demos, CEmu is the fastest iteration loop available — far superior to repeatedly flashing a physical device.

High-school and university instructors preparing classroom calculator programs also find it invaluable: test an entire exam-day program set on your Mac before distributing to thirty calculators. Competitive programmers who rely on the TI-84 in competition settings use it to prototype under time pressure.

If you just want a graphing calculator for personal math work and have no interest in writing programs, something like GeoGebra or Desmos runs in a browser with no ROM requirements and no setup. CEmu rewards the hacker mindset.

What are the best CEmu alternatives?

CEmu's nearest rival is Wabbitemu, the long-standing emulator for older TI calculators (TI-83, TI-84 Plus, TI-84 Plus Silver Edition). Wabbitemu has a broader hardware target list but does not emulate the CE hardware platform at all — if you need the color-screen CE series, Wabbitemu is the wrong tool. TilEm covers TI-73 through TI-84 Plus on Linux but similarly lacks CE support. For TI-Nspire users, Firebird Emu is the equivalent project. None of those alternatives ship the integrated eZ80 debugger that makes CEmu stand out for assembly work.

How does CEmu compare to using a physical calculator?

For development work, CEmu wins on every practical axis. Flashing new code to a physical calculator over USB takes ten to thirty seconds per cycle; CEmu reloads a saved state in under a second. The debugger capability does not exist at all on physical hardware — there is no way to set breakpoints or inspect registers on a real TI-84. The tradeoff is that battery-life and button-feel testing obviously require hardware. I treat CEmu as the primary development environment and the physical calculator as the final acceptance test.