HORIZON · TI-89 Titanium
A black hole, ray-traced.
HORIZON · in the E-Code library
Real math. Real programs. On your calculator.
Describe the problem. Get a program that runs.
Works with the TI-84 Plus CE, including the CE-T and Python editions, the TI-84 Plus and the TI-89 Titanium. Not for the TI-Nspire or Casio.
Showreel · 04 programs · real calculator screens
Watch it work
Four hard problems. Each one a real calculator program, each screen the calculator’s own.
WINDTUNL · TI-84 Plus CE
Air, bending around a wing.
WINDTUNL · in the E-Code library
IMPACT89 · TI-89 Titanium
Nudge an asteroid. Watch it miss.
MARS89 · TI-89 Titanium
Earth to Mars, step by step.
How it works
- 1
Ask
Say what the program should do. E-Code asks one clarifying question when it needs to, then writes real TI-BASIC.
- 2
Watch it run
The program runs on a virtual TI-84 or TI-89 screen, pixel for pixel, with inputs you type. Every line is checked against the real file format before you see it.
- 3
Load it on your calculator
Download the file and send it with Texas Instruments’ free software: TI Connect CE for a TI-84 (.8xp), TI Connect for a TI-89 (.89p), or the community tool TILP. For a TI-84, Chrome or Edge on a computer can also send it straight over USB (beta).
183
programs in the library
Browse the libraryReal programs, running
Five hand-verified programs, from algebra to fluid dynamics. Each one runs live on the examples page and you type the inputs yourself.
- AlgebraFree
Formula reference card
“Give me a quick formula card for the quadratic formula, the slope formula, and the distance formula — something I can flip through with a menu during practice.”
- TrigonometryFree
Law of Cosines solver
“Take two sides of a triangle and the angle between them, then find the third side with the Law of Cosines.”
- ChemistryFree
Ideal gas law solver
“Build a solver for the ideal gas law that works no matter which variable I'm missing — pressure, volume, moles, or temperature.”
- PhysicsFree
Projectile motion solver
“Projectile motion — given a launch speed and angle, find the time of flight, the max height, and the range.”
- Fluid dynamicsFree
Reynolds number / flow regime
“A fluid dynamics program that computes the Reynolds number for pipe flow and tells me if it's laminar, transitional, or turbulent.”
Live · computed in your browser
Tilt the wing
Getting it onto your calculator
Download the .8xp, send it with TI Connect CE
The standard way. TI Connect CE is Texas Instruments’ free transfer app for Windows and Mac; drag the file onto your calculator over its USB cable. Works with every TI-84 Plus and Plus CE.
Available now, every browser
Send straight over USB from the browser
Plug the calculator in and press Send; no other software. Needs Chrome or Edge on a computer. Still in beta while we finish testing it on real calculators.
Beta, Chrome or Edge on desktop
What it costs
Free
$0no account, no card
- The examples gallery and the virtual handheld
- Programs written with your own free Claude chat, every one checked by E-Code
- Pixel-exact run and byte-exact check on every program
- .8xp download and USB send
Starter
$8a month
- Programs written inside the app, no copy-paste
- Standard-level subjects
- Solve and answer-key modes
- 200k tokens a month
Plans open soon
Pro
$16a month
- Everything in Starter
- Show-work mode: every step, paced so you can copy it down
- Advanced chemistry, physics and engineering
- 500k tokens a month
Plans open soon
Plans are monthly; cancel any time. Exam mode (Press-to-Test) disables all programs on the calculator: E-Code is for homework, practice and checking your work.
Straight answers
Which calculators does it work with?
The TI-84 Plus and TI-84 Plus CE, including the CE-T and Python editions, and the TI-89 Titanium with its algebra system (exact answers, solve, derivatives, integrals). TI-89 programs download as .89p text files that the calculator converts the first time you run them. It does not support the TI-Nspire or Casio calculators.
How do I get a program onto my calculator?
With a computer and the calculator’s USB cable: download the .8xp file and send it with TI’s free TI Connect CE software, on Windows or Mac. In Chrome or Edge on a computer you can also send it directly from E-Code; that path is in beta. A phone can’t send programs to a calculator. Step-by-step guide.
Can I use these programs on a test?
Usually not. Press-to-Test (exam mode) disables every program on the calculator, and most schools require it. E-Code is for homework, practice and checking your method; follow your school’s rules on calculator use.
Do I need my own Claude account?
Only on the free tier, where your request goes through a Claude chat you paste into yourself and E-Code never sees it. Starter and Pro will write the program inside the app, with no account of your own, once plans open.
Can I cancel?
Yes, at any time. Plans are monthly, and cancelling stops the next charge.