Input unit -The input unit is formed by the input devices attached to the computer. Input devices are used to interact with a computer system or used enter data and instructions to the computer. These devices convert input data and instructions into a suitable binary form such as ASCII, which can be acceptable by the computer. Example keyboard and scanner.
Memory unit -This unit is also called storage unit it stored data and instruction which are entered through input devices and it stores an intermediate result of processing. It stores the final result of processing before these results are passed to an output. Consist of secondary storage the memory that supplements the main memory and Primary storage the memory that communicates directly with CPU enable storage of at least temporal data and instruction.
CPU (central processing unit) –It is responsible for interpreting and executing most of the commands from the computer hardware and software and also controls the operation of all other components such as memory unit, input and output devices.
Arithmetic Logic Unit – This is the area of CPU where various computing functions are performed on data. The ALU performs arithmetic operations such as addition, subtraction, multiplication and division and logical operation such as comparison AND, OR and Exclusive OR.
Output Unit – The output unit is formed by the output devices attached to the computer. Output devices are used to present result produced by the computer to the users. The output from the computer is in the form electric signals, which is then converted into human understandable form into human readable form. Example output devices the monitor and speaker.