ASCII

ASCII stands for American Standard Code for Information Interchange.

It’s the standard system used by computers to represent text. Each character is stored as a unique binary value, allowing letters, numbers, and symbols to be processed and displayed.

ASCII Character Groups

ASCII characters are divided into two main groups which allow users to interact with computers in different ways.

Control Characters

Control Characters are the first32 (0-31) ASCII Codes.

They are used to perform actionsrather than display a characteron screen.

Examples: Shift, Escape, CTRL

Printable Characters

Printable characters come after ASCII codes for the control characters. (32-255)

They are used to display a character on screen.

Examples: A, j, H, 1, 9, ?, @, !

Modern computers use control and printable characters at the same time.

For example, pressing Shift or Caps Lock is a control character. It changes how letters appear — like turning a into A.

This helps the computer understand what you want to type.

Storing ASCII Characters

Each ASCII character is stored using 8 bits. To calculate how many bits are needed to store a word or sentence:

Number of Characters x 8

Below are three examples that show this in action.

Super

Super has 5 characters.
Every character requires 8 bits to store.

5 x 8 = 40

It would require 40 bits to store the word ‘Super’.

Study Party

Study Party has 11 characters.
Remember to count spaces!

11 x 8 = 88

It would require 88 bits to store the word ‘Study Party’.

5tudy P@rty_!

5tudy P@rty_! has 13 characters.
All types of characters must be counted!

13 x 8 = 104

It would require 104 bits to store the word ‘5tudy P@rty_!’.

Understanding the different types of characters that ASCII uses — and knowing that each one is worth 8 bits — can lead to easy marks in the exam.

With that in mind, how many bits are required to store the word ‘Success’?

National 5 Target

You should be able to explain what ASCII is.

You should be able to calculate the number of bits required to store a piece of text.

You should be able to explain the difference between printable and control characters.