Computer system consists mainly of four basic unit. an input unit, a storage unit, the central processing unit and an output unit. The central processing unit further comprises: an arithmetic logic unit and the control unit, as shown in the figure: the computer to perform the functions of five business regardless of its size or make of. These are
• It takes as input data or instructions
• It stores data and instructions
• It processes data in accordance with instructions
• It controls all operations within a computer
• It gives the results in the form of the output

Input unit
This unit with these help, we enter data into a computer device. This unit allows contact between the user and the computer. Input Devices translate information into a form understandable by the computer.

CPU (Central Processing Unit)

CPU is regarded as the brain of the computer. CPU performs all types of data processing operations. It stores data, intermediate results, and instructions (program). It controls the operation of all components of the computer.

CPU itself has the following three components
ALU (arithmetic logic unit)
Memory
Control unit


The output unit
Consisting of help output unit, where we information equipment from the computer. This unit is a link between the computer and the user. Computer output device to convert the output to the user's understanding of the form.