1. Booting a computer

When a computer is first switched on, the main memory (RAM) is empty and the CPU has no instructions to follow.

So how does a computer get from this state of doing nothing to doing something useful?

This is the role of 'booting' a computer.

Booting allows the operating system to be loaded from initial switch-on.

Booting has to happen in small steps because at the point of switch-on the machine is effectively dumb. It does not know about any hard disks it may contain, or any peripherals such as the screen, keyboard, mouse - absolutely nothing.

But there is an established way of booting up a computer and the piece of software involved with this is called the BIOS.