What is digital data, and how do computers understand it? How is digital data represented, stored, shared and manipulated?

The number system that computers use is binary. Binary is a base-2 system as it only uses two digits, 0 and 1.

A binary digit, or bit, is the smallest unit of data in computing. All data (music, images, software) processed by a computer is stored in bits.

Any data or instructions sent to the CPU must first be changed into binary code, also known as machine code.

The circuits in a computer's processor are made of billions of transistors. Each of these transistors is a switch that reacts to the electronic signals it receives. The bits 0 and 1 correspond with the 'on' and 'off' states of the transistors.

A number base indicates how many digits are available in a numerical system. The denary (or decimal) system is known as base-10 because there are ten choices of digits between 0 and 9. For binary numbers, there are only two possible digits available (0 or 1), so it is also known as base-2.

In a base-2 system, each place value increases by a power of 2. The first place value is 2^{0} (1), the second is 2^{1} (2), the third is 2^{2} (4), the fourth is 2^{3} (8) and so on. We could represent 8 bits (one byte) of data using the table below.

Consider the binary number 1001 0011:

Binary | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 1 |
---|---|---|---|---|---|---|---|---|

Denary | 128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 |

This binary number represents 128 + 16 + 2 + 1. Or 2^{7} + 2^{4} + 2^{1} + 2^{0}.

The sum of these values is 147.

Therefore, the 8-bit binary number 1001 0011 represents 147 in denary.