Operating systems for computers

Some common operating systems in use are Disk Operating System (DOS), Windows-NT workstation, Windows 9x, Windows 2000 professional, Windows XP, Windows Vista, UNIX and LINUX. DOS was the lone player in this segment during initial days. Till mid 1980s, this operating system was popular. The various features of this operating system are Single user usage and batch feature. Batch feature helps to store many command in a single file which can be executed one after the other. PC DOS is the first operating system designed by IBM. But later Microsoft DOS (MS-DOS) become popular. For operation of MS-DOS, a 64K RAM is sufficient. Microsoft later released Windows-NT workstation which supports networking of computers but requires very high configuration machines. For high-end machine applications, Microsoft designed windows-95, windows-97 and windows-98. In the year 2000, Microsoft developed windows 2000 professional operating system. To work with 64-bit CPUs and to support digital media, advanced mobile computation, advanced networking and communications, Microsoft developed Windows XP and Windows Vista. UNIX and LINUX are available free of cost with multitasking features and multi-user environment.

Network topologies

A network topology is a layout of the cables, computers and other peripheral devices that are connected in a computer network. A fine classification divides network topologies into four different categories. They are star topology, ring topology, bus topology and mesh topology.  In star topology, computers and network devices are connected directly to a central server computer (hub). Any device which is connected to the hub is called as a node. In a ring topology, all the computers and network devices are connected in the form of ring. In a bus topology, computers and network devices are connected to a single cable. This cable or wire is known as bus. A network topology in which computers and network devices are interconnected with one another in the form of a mesh is called mesh topology.