Keyboard to binary

When you press a key, the computer does not get a letter. It gets a code made of 1s and 0s. Type something and watch both screens.

You press a keyComputer gets binaryScreen shows the letter

Binary (what the computer sees)

  1. Waiting for a key…

Type a letter to see how capital and small letters differ in binary.

What is happening?

Every key on the keyboard has a number, called its ASCII code. When you press a key, the keyboard sends that number to the computer in binary. The computer then looks up the code and draws the matching letter on the screen.

For example, the capital letter A is code 65, which is 01000001 in binary. Each 0 or 1 is called a bit, and 8 bits make one byte. So every letter you type uses one byte.

Things to try

  • Type your name. How many bytes does it use?
  • Type a and then A. Which bit changes?
  • Press Space and Enter. They have codes too, even though you can’t see them.
  • Type the digit 1. Is its binary code the same as the number one?

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