GNDU B.Com (Bachelor of Commerce)

Chapter 4: Operating Systems and Fundamentals of DOSSemester 1 — summary, notes, extra questions & MCQ quiz

Summary

An operating system (OS) is the most important system software, acting as an interface between the user and the computer hardware and managing all the resources of the system. Its role is to make the computer usable and to control its operation. The main functions of an operating system include process management (controlling the execution of programs), memory management (allocating and freeing memory), file management (organising data into files and directories), device management (controlling input and output devices) and providing security and a user interface. Operating systems are of several types: single-user and multi-user systems, batch processing, multiprogramming, time-sharing, real-time and distributed operating systems, each suited to different needs. A classic example studied at the fundamentals level is DOS (Disk Operating System), a single-user, command-line operating system in which the user types commands at a prompt. DOS commands are of two kinds: internal commands, which are built into the command interpreter and loaded into memory at start-up (such as DIR, COPY, DEL, CLS and TYPE), and external commands, which exist as separate program files on disk and are loaded only when called (such as FORMAT and CHKDSK). A batch file is a text file containing a series of DOS commands that execute one after another automatically. Booting is the process of starting up the computer and loading the operating system into memory; it is of two types, cold booting (starting from power-off) and warm booting (restarting an already running system).

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