How to Program a TI-84 — TI-BASIC for Beginners
TI-BASIC is the built-in programming language on every TI-84 Plus and TI-84 Plus CE. This guide teaches the fundamentals — variables, input and output, loops, and conditionals — and walks you through a complete program you can write and run right now in the free TI-BASIC editor at Calc84, no physical calculator required.
5→X), print with Disp, get input with Prompt or Input, branch with If/Then/Else, and repeat with For or While. You can write, run, and debug all of this in the free Calc84 TI-BASIC editor. For the full command reference, the community wiki at TI-BASIC Developer is the standard resource.
What is TI-BASIC, and why learn it?
TI-BASIC is a beginner-friendly programming language that ships inside every TI-84 calculator. It looks a lot like an early dialect of BASIC: commands are short English words (Disp, Prompt, For), and a program is simply a list of instructions the calculator carries out one at a time.
Two groups of people learn TI-BASIC. The first are students in computer-science classes or TI-84 programming electives, where writing a small program is often a required project. The second are students who want to automate the repetitive math they do every day — a quadratic-formula solver, a distance formula, or a "guess the number" game to run between classes. In both cases the payoff is the same: you stop being a button-pusher and start telling the calculator what to do.
The best way to learn is to type code and watch it run. The Calc84 TI-BASIC editor runs your programs in the browser, so you can experiment without owning a physical calculator. When you are ready, you can export your program as a plain-text file and type it into a real TI-84.
Your first program: Hello, world
Every language starts the same way. In the editor, create a new program and type this single line:
Press Run and the output console prints HELLO WORLD. The colon at the start marks a line of code (in TI-BASIC, a colon separates commands on the same line). Disp is short for "display" and prints whatever follows — text in quotes, or a number, or a variable.
Variables and the STO→ arrow
A variable is a named box that holds a value. On the TI-84 you assign a value with the STO→ key, written as a right-pointing arrow. To store the number 5 into the variable X:
This prints 5. The arrow always points toward the variable: whatever is on the left gets stored into whatever is on the right. The TI-84 has single-letter variables A through Z, plus the Greek letter theta (θ). You can also update a variable using its own current value:
This prints 11. That pattern — X+1→X — looks strange at first (a number can't equal itself plus one), but it is not an equation. It means "take the current value of X, add 1, and store the result back into X." It is the single most common line you will write, because it is how loops count.
Getting input: Prompt and Input
A program that always prints the same value is not very useful. To make a program respond to the user, you ask for a value with Prompt or Input.
When this runs, the calculator pauses and asks for a value for A. Enter 7 and it prints 14. Prompt can also request several variables at once:
Input does the same thing but lets you attach a custom message, which makes your program much clearer to use:
Making decisions: If / Then / Else
Programs make choices with If. The full form uses Then and End to group several commands, with an optional Else for the "otherwise" case:
The condition X>0 is either true or false. If true, the calculator runs the commands between Then and Else; if false, it runs the commands between Else and End. You can compare with =, ≠, >, <, >=, and <=.
Repeating: For and While loops
Loops run a block of code many times, which is where programming starts to save real effort. A For loop runs a fixed number of times:
This prints the numbers 1 through 5. The For line means "start I at 1, keep going while I is at most 5, and add 1 to I each time." A While loop runs while a condition stays true:
This prints 1 through 9 and stops when X reaches 10. Notice the X+1→X line from earlier — without it, X would stay 1 forever and the loop would never end.
A complete program: a factorial calculator
Let's put the pieces together. A factorial (n!) is the product of every whole number from 1 up to n, so 5! = 1×2×3×4×5 = 120. We can compute it with a loop and an accumulator variable:
How it works, line by line: Prompt N asks for the number. 1→F starts the answer at 1. The loop multiplies F by each value of I from 1 up to N. After the loop, Disp F prints the result. Enter 5 and you get 120.
This is the same pattern behind the quadratic-solver and geometry templates built into the editor: get input, loop or compute, then display the answer. Try changing the program to compute 2^N instead, or to sum the numbers from 1 to N.
Transferring your program to a physical TI-84
The Calc84 editor exports your work as a plain-text .txt file. To move a program onto a real calculator, you have two options:
Binary calculator files (.8xp) are not generated by the editor — it works in plain text, which is why typing by hand or using TI Connect is the way to get code onto hardware. For syntax details and edge cases, TI-BASIC Developer is the reference the community maintains.
What the Calc84 editor runs — and what it does not
The editor's interpreter supports the core of TI-BASIC that covers most beginner projects: Disp, Prompt, Input, If/Then/Else/End, For(/End, While/End, Lbl/Goto, variable assignment, and basic arithmetic (including √( and exponents).
It does not yet run the graphics commands of a full TI-84, such as Output(, ClrHome, DispGraph, or getKey. If you need those, you will want a full emulator or a physical calculator. For learning the fundamentals of programming — variables, input, output, decisions, and loops — the editor gives you everything you need and runs it instantly.
Ready to start? Open the TI-BASIC editor, create a new program, and type the Hello World example above. When it runs, you have written your first TI-84 program. From there, work through the factorial example, then modify it and see what happens — that experimentation is how you actually learn to program.
TI-BASIC programming questions, answered
Is TI-BASIC a good first programming language?
Yes, for one specific reason: the feedback is instant. You type a line, press Run, and immediately see the result — there is no compiler, no project setup, and no confusing environment. The command set is small enough to learn in an afternoon, and the concepts you pick up (variables, loops, conditionals) transfer directly to Python, Java, or any other language you learn later. The main limitation is that TI-BASIC's graphics and structure are simpler than a modern language, so it is a great starting point rather than a full introduction to professional programming.
What is the difference between TI-BASIC and Python on a TI-84?
TI-BASIC is the calculator's built-in language and works on every TI-84 model. Python is only available on the TI-84 Plus CE Python edition (and the newer TI-Nspire), where it runs alongside TI-BASIC. TI-BASIC uses short commands like Disp and Prompt, while Python uses words like print() and input(). If you are preparing for a general programming class, Python is the more relevant language, but TI-BASIC is simpler to start with and runs on any TI-84.
How do I store a program's answer so I can reuse it in another calculation?
Assign the result to a variable and leave it there. For example, if a program computes a factorial and stores it with F*I→F, the final value stays in F after the program ends. You can then use F in another program or in the main calculator. On a physical TI-84, variables persist until you clear RAM; in the Calc84 editor, they persist for the session. To pass a value deliberately, just make sure your program ends by storing its answer into a variable you name.
Why does my program show a syntax error when I run it?
The most common causes are a missing colon at the start of a line, a mismatched End (every Then, For(, and While must be closed with its own End), or using the minus sign − when you mean the negative sign (−). Check that text is wrapped in quotes, that If statements are on their own line before Then, and that you are not reusing a variable name the calculator reserves. Fix one line at a time and re-run — the error is almost always on the line right before the one that fails.
Can I write a game in TI-BASIC?
Yes — simple text games work well. A classic first project is a "guess the number" game: store a secret number in a variable, use a While loop to keep asking for guesses, and If statements to tell the player whether to guess higher or lower. The Calc84 editor supports the control flow you need, though its interpreter does not yet include the randInt command for random numbers or the screen-drawing commands (Output(, getKey) that more visual games rely on. On a physical TI-84 you would add randInt(1,100) to generate the secret number; in the editor, pick a fixed number for now.
