BIOS

Computer Switched on

RAM is empty so there are no instructions to follow

ROM contains the BIOS so the start up can be controlled

Is there a steady power supply

Send a 'REST' command to the CPU

Use the command within the hard-coded section to carry out a specific instruction somewhere within the BIOS

The location in the BIOS contains a 'JUMP' command to begin the boot

The BIOS does POST checks (Power On Self Test)

Are POST checks okay

BIOS emits a series of beep codes if there is a problem

Carry onto the next BIOS

This BIOS starts up the video card allowing you to see something on the screen

The system looks for other peripherals like the hard disk and signals to start spinning

BIOS contains details of the hardware when it is working it looks for an OS to boot

After a bootable drive is found, the FDE cycle processes the instructions in the 'BOOT SECTOR'

The 'BOOT SECTOR' is the first region of storage for as device

HDD contains the MBR (Master Boot Record)

The MBR is a data table which indicates where fragments are located on the HDD

The CPU jumps to tht fragment before continung

The MBR points the CPU in the direction of the 'PRIMARY PARTITION' of the OS

The CPU will execute any code now in the BOOT SECTOR of the PRIMARY PARTITION

This code is called the BOOT LOADER

The BOOT LOADER will first load the OS kernel into the memory

Now the kernel is loaded various other device drivers can be loaded

The GUI is loaded with any personal settings

The computer is ready to use