2. Storage Capacity

Data can be stored either in the 'internal memory' or on a 'storage device'.

The amount of data and instructions that can be stored is measured in 'bytes'.

One byte contains 8 bits (short for Binary Digit). This is the smallest unit of data that can be stored. Each 'bit' is represented as a binary number, either 1 or 0.

A single keyboard character such as the letter A or T takes one byte of storage. A single mp3 music track is typically 3Mb

We normally refer to the capacity of a storage device in terms of Kilobytes (kB), Megabytes (MB), Gigabytes (GB) - or even Terabytes!

Storage sizes
Design Name Author
Bit Smallest unit of data, either a 0 or 1
Byte 8 bits
Kilobyte (kB) Assumed to be 1,000 bytes. In reality it is really 1,024 bytes
Megabyte (MB) 1,000 kilobytes (1,024 Kb)
Gigabyte (GB) 1,000 Megabytes (1,024 Mb)
Terabyte (TB) 1,000 Gigabytes (1,024 Gb)