BIOS

Flowchart nodes

• 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