The TI-84 isn't just a calculator — it's a small programmable computer, and writing your own TI-BASIC programs is a great introduction to programming logic while also giving you custom tools for recurring homework tasks. This guide walks through creating your first program from scratch.
Introduction
TI-BASIC is the built-in programming language of the TI-84, designed to be readable and approachable even for students with no prior coding experience. Programs are written and run directly on the calculator, with no separate compiler or computer needed.
This guide covers creating a new program, using input and output commands, storing and using variables, controlling program flow with If-Then statements and loops, and troubleshooting the most common beginner errors.
Creating Your First Program
Press PRGM, arrow to NEW, and press ENTER. Type a name for your program (up to 8 characters, letters and numbers, starting with a letter) and press ENTER again. You are now in the program editor, where every line you type becomes a line of the program, automatically prefixed with a colon.
A simple first program might display a greeting: type Disp "HELLO" (found under PRGM → I/O → Disp) then press 2ND, MODE (QUIT) to exit the editor. Run it anytime by pressing PRGM, selecting the program name from EXEC, and pressing ENTER.
Input, Output and Variables
The Input command (PRGM → I/O → Input) pauses the program and waits for the user to type a value, storing it into a variable — for example Input "RADIUS?",R prompts for a value and stores it in R. The Disp command then displays text or the result of a calculation, such as Disp "AREA=",πR².
Variables in TI-BASIC are typically the same single letters (A through Z) used elsewhere on the calculator, plus lists and matrices for more complex data. Because these variables are shared calculator-wide, a program that uses variable X will overwrite whatever value X held before running — keep this in mind if a program produces unexpected side effects elsewhere.
Using If-Then and Loops
If-Then (found under PRGM → CTL) lets a program branch based on a condition: If X>0 followed by Then on the next line, then the commands to run, then End on its own line closes the block. Add Else between Then and End to specify what happens when the condition is false.
For repetition, For(variable,start,end) followed by commands and then End repeats a fixed number of times, while While condition followed by commands and End repeats as long as a condition stays true. These three control structures — If-Then, For, and While — are enough to build almost any simple program, from unit converters to quiz generators.
Debugging Common Program Errors
When a program throws an error, the calculator shows the error type and offers Quit or Goto — selecting Goto jumps directly to the offending line inside the program editor. The most frequent beginner mistakes are forgetting a matching End for every For, While, or If-Then block, and using a variable in a calculation before it has been assigned a value.
If a program seems to run forever, you likely have an infinite loop — a While condition that never becomes false, or a For loop with an incorrect end value. Press ON to manually break out of a running program at any time, which brings up a Quit/Goto prompt just like an error.
Where to Find More Programs
Texas Instruments hosts an official library of free programs and activities on their education website, organized by subject area, which is a good source of vetted, working examples to study and adapt. Many programs can also be transferred between calculators using a USB link cable and TI Connect CE software.
Reading other people's short programs is one of the fastest ways to pick up new TI-BASIC techniques — try retyping a simple program from scratch rather than only transferring it, since typing each line reinforces the syntax and structure far better than copying a finished file.
Further Reading & Sources