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Python4 min read

How Python programs actually run on your TI-84

The `.py` files this app generates don't run from the calculator's BASIC environment. Here's what happens when you transfer one and hit `prgm`.

Every program ti84-app generates is a Python program, not TI-BASIC. The TI-84 Plus CE Python edition (2019+ hardware) ships with a separate Python app that lives alongside the classic TI-BASIC interpreter. If you've only used the calculator for its factory functions, the flow below is the part that isn't obvious.

What the .py file actually is

It's a plain-text MicroPython file — the same language you'd type in a laptop terminal, but stripped down to fit in the calculator's 154 KB of usable RAM. The interpreter is called CE Python internally. It understands math, random, ti_system, ti_plotlib, and ti_hub, and nothing else — no numpy, no os, no requests.

Transferring the file

  1. Plug the calculator into your laptop with the mini-USB cable that came in the box (or any mini-USB, they're cheap).
  2. Open TI Connect CE (free from Texas Instruments). The calculator should appear in the left sidebar.
  3. Drag the .py file onto the calculator's icon — or use Actions → Send to Calculator.
  4. TI Connect rewrites the filename to uppercase and drops anything over 8 characters, which is why ti84-app emits names like QUAD.py and PYTHAG.py.

Launching the program

On the calculator itself:

  1. Press prgm.
  2. You'll see two tabs at the top: EXEC (run) and EDIT. Arrow-right to the Python sub-section.
  3. Scroll to your program by name and press enter twice — once to select it, once to execute.

The program runs inside a Python shell. If you wrote it (or if ti84-app wrote it for you) using the menu-driven pattern, you'll see a numbered list and a ?> prompt waiting for a keypress.

Editing on-device

If something goes wrong or you want to tweak a formula, you can edit on the calculator. From prgm, pick the EDIT tab, find the program, and press enter. The on-device editor is painful but functional — 2nd + arrow keys jumps word-by-word, alpha switches to letters, alpha twice locks into letter mode.

For anything longer than a one-line tweak, edit on your laptop and re-transfer. The calculator editor is for emergencies.

Common gotchas

  • File not showing up in the prgm menu? The calculator caches the file list. Press 2nd + mem → 2:Mem Management/Delete… → PY programs to force a refresh, then exit and re-open prgm.
  • "ImportError" on launch. You tried to import something outside the allowlist. Every ti84-app program is already restricted to math, random, and the ti_* modules, so this only happens if you've hand-edited.
  • Program runs but shows nothing. Probably exited on a blank menu() with no options. Press clear and check the code — menu() must have at least a 0:EXIT branch.