THE COMPUTER BOOT PROCESS

The BOOTING process

This is what we call starting up or turning on your computer. This takes several minutes as lots of things happen very quickly between the time you turn on and when the computer will be ready for use. All data and instructions are stored in the RAM while the computer is on even the OPERATING SYSTEM too.

The BOOT PROCESS is when the OPERATING SYSTEM is loaded into the RAM. See steps involved....

1.       Powering the CPU activates the BIOS (Basic Input / Output System)

2.       The BIOS checks that all attached devices are in place. This is referred to as POST (Power On Self-Test)

3.       The operating system is then loaded into the RAM

4.       Configuration and Customization settings are checked and loaded. In the process, beeping and lights illuminates on various devices....

 

Now I will discuss the BOOT PROCESS one after the other

1.      ACTIVATING BIOS - The CPU activates the BIOS, it is a program that manages the data between the Operating system and all the input and output devices attached to the system. BIOS is also responsible for loading the OS from its permanent location on the hard drive to the RAM. BIOS is stored on a special ROM chip on the mother board.

2.      PERFORMING THE POWER SELF TEST - First the BIOS ensures that essential peripheral devices are attached and operational. This is a process called POST. The POST consists of a test on the video card and video memory, a BIOS identification process (the BIOS version, manufacturer and data are displayed on the monitor), and a memory test to ensure memory chips are working properly. The BIOS compares the results of the POST with the various hardware configurations that are permanently stored in CMOS. CMOS is a special kind of memory that uses almost no power. A little battery provides enough power so its contents will not be lost after the computer is turned off. CMOS contains information about the system's memory, types of disk drives, and other essential input and output hardware components. If the results of the POST compare favourably to the hardware configurations stored on CMOS, the BOOT PROCESS continues.................

3.      LOADING THE OPERATING SYSTEM - Next, BIOS looks through the storage disks for the system files (the main files of the operating system). It then loads the OS from its permanent storage location on the hard drive to the RAM. Once the system files are loaded into the RAM, the KERNEL (supervisor program) is loaded. The KERNEL is the essential component of the OS that is responsible for managing the processor and all other components of the computer system. The KERNEL stays in the RAM when the computer is powered on and it is called memory resident. Other system files that are less important stays on the hard drive and are copied to RAM when needed. They are called non-resident. Once the KERNEL is loaded, the operating system takes over the control of the computer.

4.      CHECKING FURTHER CONFIGURATIONS AND CUSTOMIZATIONS - Although the CMOS checks the configuration of memory and essential peripherals at the beginning of the boot process, the operating system continues to check the configuration of other system components in this last stage of the boot process. The registry contains all the different configurations used by the OS as well as by other applications. It contains the customized settings you put into place, such as mouse speed, the display settings for your monitor and desktop as well as instructions as to what programs should be loaded first.

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