A computer has four main functions: input, processing, output, and storage. It has five key components that enable these functions: the central processing unit (CPU), memory, input units, output units, and storage. The CPU contains the control unit which directs the flow of data and signals, and the arithmetic logic unit which performs basic math and logic operations.

1. Components of the
Computer

2. A computer does mainly the following four functions :
 Receive input – Accept information from outside through various input
devices like the keyboard, mouse etc.
 Process information – Perform arithmetic or logical operations on the
information.
 Produce output – Communicate information to the outside world
through output devices like monitor, printer etc.
 Store information – Store the information in storage devices like hard
disk, floppy disks etc.
There are five components of the computer which perform the previous
four functions :

3. CENTRAL PROCESSING UNIT (CPU)
The part of the computer that executes program instructions is
known as the processor or central processing unit (CPU). CPU
has two parts – the control unit and the arithmetic logic unit.
In a microcomputer, both are on the microprocessor chip.
CPU
Microprocessor

4. Control Unit
 The control unit tells the rest of the computer system how to
carry out a program’s instructions.
 It directs the movement of electronic signals between memory
– which temporarily holds data, instructions and processed
information – and the ALU.
Arithmetic Logic Unit
 Performs basic arithmetic operations such as addition and
subtraction.
 Performs logical operations such as AND, OR, and NOT.
 Most modern ALUs have a small amount of special storage units
called registers that can be accessed faster than main memory.

5. Input Unit
 An input device is any machine that feeds data into a
computer.
 Computer receives or accepts information as input from
the user for the further processing.
Keyboard Mouse
Speakers Touchpad

6. Memory
RAM and ROM
Memory – also known as the primary storage or main
memory – is a part of the microcomputer that holds data
for processing, instructions for processing the data.
Random Access Memory (RAM)
A type of computer memory
that can be accessed randomly.
Read Only Memory (ROM)
A type of computer memory on
which data can be prerecorded.

7. Output Units
 A device through which results stored in the
 computer memory are made available outside the
computer system.
 It produces and communicate information to the user
through output devices like monitor, printer etc.
Monitor Printer