Architecture of Computer6 min read


Computer Architecture is a collection of rules and methods used in computer engineering to define the functionality, organization, and implementation of computer systems. In other words, computer architecture encompasses the creation of instruction sets, microarchitecture, logic, and implementation.

Computer architecture describes how a computer’s hardware components are connected, as well as the data transmission and processing methods used. Different computer architecture configurations have been designed to improve data processing by speeding up data movement.

There are six main functional parts of the computer architecture:

  1. Input Unit
  2. CPU (Central Processing Unit)
  3. ALU (Arithmetic & Logical Unit)
  4. Control unit
  5. Memory or Storage Unit
  6. Output Unit
Architecture of computer
architecture of computer


The main function of the input unit is to receive the information or data from any input device and make them available in machine-readable form to the computer. All the information handled by a computer system is coded with ‘O’ and ‘1’, which are known as Binary digits.

The various input devices which are commonly used are Magnetic tapes, Magnetic disks, Floppy disks, CD ROMs, Mouse, Audio response terminal, Keyboard, Scanner, etc.

In short, the following functions are performed by an input unit :

  1. The input unit accepts the list of instructions and data from the outside world.
  2. It converts these instructions and data into the computer-acceptable form.
  3. It sends the converted instructions and data to the computer to be processed further.

2. CPU (Central Processing Unit)

The Central Processing Unit (CPU) is the brain of every computer system. The brain makes all major decisions in the human body, and other parts of the body act as guided by the brain. Similarly, in a computer system, all major calculations and comparisons are responsible for the activity and controlling the operations of another unit of the computer system.

In a microcomputer, the components of the CPU are mounted on the main circuit board are called the “Motherboard”. A microprocessor chip contains the circuit and special storage locations called registers i.e. needed to perform the arithmetic, logic, and control functions are Some important points to remember about CPU :

  1. This unit forms the main brain of the computer.
  2. CPU has two distinct components Control Unit and ALU.
  3. The control unit directs the binary instructions.
  4. The control unit manages the data input, process, and output devices.
  5. ALU is made for two distinct operations, Arithmetic and Logical.
  6. It does all kinds of mathematical operations.
  7. ALU also supports less than, greater than kinds of logical operations.
Central processing unit

3. ALU (Arithmetic & Logical Unit)

The Arithmetic Logic Unit executes arithmetic and logical operations. Arithmetic operations include addition, subtraction, multiplication, and division. Logical operations compare numbers, letters, and special characters.

Comparison operations test for three conditions:

  1. Equal-to condition in which two values are the same.
  2. Less than a condition in which one value is smaller than the other.
  3. Greater-than condition in which one value is larger than the order.
  4. Relational operations (=,<,>) are used to describe the comparison operations used by the arithmetic logic unit.

4. Control Unit

Control unit

The Control Unit of the CPU controls the entire operation of the computer. This section of the computer is really acting as the brain of the computer. It also controls all other devices connected to the CPU, such as memory, input, and output devices. The control unit reads an instruction from memory, decodes it, interprets it to figure out what tasks need to be done, and then sends a suitable control signal to carry out the instruction. It keeps the machine running in order and guides its work. The control unit gives the signals to ALU for operations to be performed and also generates timing and control signals and provides them for all operations.

The control unit controls the data flow between the CPU and other peripherals. It provides status, control, and timing signals that the memory and the input/output devices require. The instructions are fetched from memory one by one for execution under the direction of the control unit until all of the instructions have been executed.

5. Memory Unit

The Memory Unit of a computer is often called main memory or primary memory. It is generally the third component of the CPU. It holds data and instructions for processing. When we install software from a floppy disc, hard disc, or CD-ROM, it is saved in the main memory.

The memory of a computer is more like a predefined working place, where it temporarily keeps information and data for performance. When the job is performed, it clears its memory and memory space is then available for the next job to be performed. When the power is turned off, everything in the memory is deleted and cannot be retrieved.

Hence secondary memory space is needed to store data and information permanently for later use. A number of bits (binary digits 0 and 1) are used to store data in the memory. A Bit is the smallest unit in memory and an 8 bit is called a byte and a group of 4 bits is called a nibble.

Following are some types of main memory

  1. RAM
  2. ROM
  3. Cache
  4. Dynamic RAM
  5. Static RAM
  6. Flash memory
  7. Virtual memory

The main purpose of the primary storage unit in the computer system

  1. Holds data/instructions temporarily during instructions.
  2. Holds intermediate results.
  3. Its size affects speed, power, and capability.
  4. The main memory receives and transmits all inputs and outputs.


An Output Unit’s work is the polar opposite of an input unit’s. It communicates knowledge and computation outcomes to the outside world. As a result, it connects the machine to the outside world. Since computers operate in binary code, the results they generate are often binary code. As a result, before releasing the results to the public, they must be translated into a human-readable format.

An output unit performs the following function:

(a) It embraces the computer’s findings, which are in coded form and therefore difficult to comprehend.
(b) It converts these coded results to a human acceptable form.
(c) It distributes the converted results to the rest of the world. Some popular output devices are VDU, Printer, Plotter, Speech Synthesizer and Coder, etc.


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