Computer Knowledge - Exam Oriented
1. Operating Systems-
Operating Systems - An Operating system is a program that controls the execution of application programs and acts as an interface between the user of a computer and the computer hardware. An operating System (OS) is an intermediary between users and computer hardware. It provides users an environment in which a user can execute programs conveniently and efficiently. In technical terms, it is software which manages hardware. An operating System controls the allocation of resources and services such as memory, processors, devices and information. Definition of an operating system is a program that acts as an interface between the user and the computer hardware and controls the execution of all kinds of programs.
There are several classes of operating systems and many variations: Mainly DOS. UNIX and Mainframe OSs from IBM. DOS (Disk Operating System) later became Windows while UNIX led to different variants such as: Linux, Sun Solaris, Free BSD, AIX.. etc. IBM operating systems were mainly targeted towards mainframes and some of the well known ones are OS/360. OS!390 and OS/400. Apple Macintosh can also be considered as a separate class of OS rather than a variant of UNIX. DOS was the first disk based OS which was developed for IBM PC by Microsoft.
It was concerned about keeping OS, application programs and all user files on a disk and managing them through set of commands called DOS commands. There are two well known variants of DOS called PC-DOS (Personal Computer DOS) and MS-DOS (Microsoft DOS). PC-DOS was developed and sold with IBM PCs while MS-DOS was sold in open market. DOS was simple to use and learn therefore Microsoft was able to win a large market share among other PC OSs.
Microsoft released their first version of GUI (Graphical User interface) based OS called Windows 1.0 on 1985. However. only Windows 3.1 was commercially successful Early versions of Windows were just an application miming on top of DOS, behind the screen GUI was actually issuing DOS commands. With the success of Windows 3.1 Windows 95 was introduced. Then with the introduction of �Windows 98� Microsoft was able to purely escape from DOS and built a compute GUI based OS which does not depend on DOS. From year 2000 onwards Microsoft has released number of versions of Windows. Like, Windows Vista, The Most Popular Windows XP, Recent Version Windows 7 and Windows 8.
One of the most important OS to be discussed is the UNIX. It was developed in 1969 at Bell Labs by Ken Thompson and Dennis Ritchie. UNIX is still being used with large number of variants and versions.
Another important OS is LINUX. Linux was developed by Linus Torvalds in 1991. Linux is a UNIX like OS developed originally for Home PCs. The most important thing about Linux is its totally free. You are even given the source code of the OS. Since its freely available many people around the world had studied and improved it. Therefore Linux is a complete OS which is stable, reliable and efficient compared to most other Oss. It also supports excellent networking facilities. If you compare Windows and Linux ; Linux requires lesser disk space, memory and processing power than Windows.
