Operating system Introduction
Operating system is a bridge between a user and the hardware components of a computer. Elements of operating system are Booting loader program, control program and services program. Booting loader program is used to boot the OS of the system. Control program is used to control I/O operation. Service Program provides different types of services to both the user and the system. Loading of operating system (DOS) files into main memory is called booting up the system. Three essential files are loaded into main memory: IO.SYS, MSDOS.SYS and COMMAND.COM. To boot up the system, firstly IO.SYS and MSDOS.SYS files are loaded into the main memory. The loading of CONFIG.SYS is optional. It is used to configure the computer system. Now, the command interpreter of DOS - COMMAND.COM is loaded into the main memory. At last, AUTOEXEC.BAT file is loaded. Finally, the system’s default drive will be displayed. Basic Input and Output System (BIOS) is a pre-installed software, which is used by the computers to start up. It is a small program that controls various electronic devices attached to the main computer system. It also manages data flow between the computer’s operating system and attached devices such as keyboard, hard disk, printer etc.