What is computer ?

Computer Definition

·        Computer is an abbreviation for general-purpose stored-program electronic digital computer. It is an electronic machine that perform tasks, such as mathematical calculations or electronic communications, under the control of a set of instruction called program.

·        A computer is an electronic device that accepts data so that useful information can be generated.

·        Computer is a machine that can follow instruction to alter data in a desirable way and performs at least some operations without human intervention.

·        Computer is an electronic device capable of performing complex computation in a short time.

                     

              Elements of a computer

•      Hardware
•      Software
•      People ware

         Classifications Of Computers

1.     .. Minicomputer – It is the next large computer which serves as a computing device either rock-mounted or small enough to fit in a desktop. Also, it is a multiprocessing system capable of supporting 4 to about 200 users simultaneously.
2.        Microcomputers – are small desktop system with limited input and output device that is suitable for small business and domestic use. It consists of 4 KB to 64 KB storage location.
3.        Mainframe – are computers which are capable of handling large systems that can handle hundreds of users, stored large amounts of data and process transactions at a very high rate.
4.         Supercomputers – are the biggest, fastest and the most expensive computer  that can process trillions of the data in one second.

OS (Operating System ) – collection of system programs and routines that reside in the computer      memory.

Functions of an Operating System

• Schedule input and output operations.
• Schedules work of jobs according to its priority.
• Communicate with human operator.
• Handle interruptions and monitor system status.
• Log the jobs that are finished and currently being executed.
• Control system access and data security functions.
• Facilitate in locating and debugging errors.
• Handle multi programming.

Tape Operating System – operating system that stored in magnetic tapes.

Disks Operating System – operating system that stored in magnetic disks.