Understanding Boot and Reboot Procedures in Windows Operating System

Boot Process

• The boot process starts with the loading of CONFIG.SYS and AUTOEXEC.BAT files, followed by the running of COMMAND.COM and WIN.COM.
• This is an automatic process in Windows OS, where necessary device drivers are loaded, operating system components are initialized, and the desktop is set up.

Boot and Reboot Procedures

• A personal computer is said to boot itself, meaning it loads a small program into memory when power is applied.
• The boot process can be restarted in two ways: Warm Reboot and Cold Reboot.
• Warm Reboot: Pressing Ctrl+Alt+Del keys can restart the system.
• Cold Reboot: Turning the computer off, waiting for 5 seconds, and then turning it back on.

BIOS

• The BIOS library has functions to operate and control system peripherals, accessible through an external software.
• Users can perform tasks such as setting the system clock, enabling/disabling system components, configuring hardware, selecting boot drives, and setting password prompts through the BIOS user interface.
• There are two types of BIOS: Legacy BIOS and UEFI.
• Legacy BIOS: Used in older motherboards, controls CPU and computer components, but has limitations (e.g., can't handle drives larger than 2.1 TB).
• UEFI: Can accommodate 2.2 TB or larger drives, unlike Legacy BIOS.

Accessing BIOS Setup

• The BIOS setup can be accessed by pressing a specific key or combination of keys during the startup process, before the Windows logo appears.
• Common keys to access BIOS setup include F1, F2, F10, F12, Del, or Esc.

MS-DOS

• The computer locates and reads the boot track, which contains an IO.SYS loader that loads IO.SYS into memory and turns control over to it.
• A hidden, system, read-only file named MSDOS.SYS is created in the root of the boot drive.

Computer Startup

• Startup is the process of preparing the computer, operating system, hardware, or software for operation.
• This process is also referred to as boot or boot up.

PC Start-Up Sequence

• When a PC is turned on, it starts itself automatically, running a permanently installed program that loads an operating system.
• The program can perform useful tests before loading the operating system.

Booting Steps

• Step 1: BIOS is loaded.
• Step 2: BIOS performs Power on Self-Test (POST).
• Step 3: Loading of the operating system.
• Step 4: System configuration.
• Step 5: Loading system utilities.
• Step 6: User authentication.

POST (Power On Self Test)

• The first program executed when a PC is turned on or reset.
• Contained in the motherboard BIOS ROM, it verifies the viability of the hardware necessary to run a computer's OS and applications properly.
• If the software isn't working, the BIOS produces an error message.