Booting The Windows Operating System

Each time the computer is switched on; it goes through a series of steps before the user is permitted to interact with the system. These initial steps are collectively known as booting and the process is called as the Boot process.

Stages of The Boot Process

Windows XP boots in stages. Let us discuss the different stages.

Power On Self Test (POST)

Power On Self Test or POST is a set of instructions stored in the ROM that checks each functional area of the computer. These instructions form a part of the ROM-BIOS. The POST checks RAM, tests the connections to the various hardware devices like the keyboard, VDU and disk drive and reports problems encountered.

The next stage is the bootstrap process.

Bootstrap Process

The name of this process originates from an American expression, pull yourself up by your boot straps which means, prepare yourself. During this process, the OS is loaded into RAM. Familiarity with the boot process helps in understanding the OS better.

The bootstrap process comprises of two sequences:

• Preboot Sequence

• Actual Boot Sequence

Preboot Sequence

The bootstrap process consists of loading the components of the OS into the internal memory, (RAM) of the computer. These components are :

• Kernel – This is a program that acts as an interface layer between the user and the hardware components. The kernel hides the hardware details from the user.

• Device Drivers – These are programs that run various devices attached to the computer. For example, the disk drive and the mouse have their own device drivers.

Actual Boot Sequence

The actual boot sequence succeeds the preboot sequence. This sequence gathers information about hardware and drivers and prepares windows XP to load. Windows XP requires certain files in order to boot. They are :

• Ntldr – Loads the OS

•    Boot.ini – Builds the OS selection menu that is displayed during the booting process

• Ntdetect.com – Examines the hardware available and builds a hardware list.

Note : All these files are hidden and read only. This ensures that they are not modified or damaged accidentally.