COMPONENTS OF COMPUTERS

A computer is a combination of hardware and software.

• Hardware refers to the physical components of a computer that can be seen and touched, such as the motherboard, memory devices, monitor, keyboard, and other equipment.
• Software refers to a set of programs or instructions that tells the computer what to do.

Both hardware and software work together to make a computer system function.

BASIC WORKING OF A COMPUTER: IPO CYCLE

Every task performed by a computer generally follows the Input–Process–Output (IPO) Cycle.

INPUT

│

▼

PROCESSING

│

▼

OUTPUT

• The Input Unit accepts data and instructions.
• The Central Processing Unit (CPU) processes the data.
• The Output Unit produces the desired result.
• The Memory Unit stores data, instructions, and intermediate results during processing.

Basic Components of a Computer

COMPUTER

│

┌─────────────────┼─────────────────┐

│                 │                 │

INPUT UNIT          CPU            OUTPUT UNIT

│

┌──────────────┼──────────────┐

│              │              │

ALU       MEMORY UNIT     CONTROL UNIT

1. INPUT UNIT

The Input Unit consists of devices used to enter data and instructions into a computer.

It creates a link between the user and the computer. Input devices convert information into a form that can be understood and processed by the computer.

Examples: Keyboard, mouse, scanner, microphone, joystick, etc.

2. CENTRAL PROCESSING UNIT (CPU)

The Central Processing Unit (CPU) is often considered the brain of the computer.

It performs all major data-processing operations, stores data and intermediate results, and controls the operation of all other parts of the computer.

Main Functions of the CPU

• Performs data-processing operations.
• Stores data, intermediate results, and instructions.
• Controls the operation of all parts of the computer.

The CPU consists of three major components:

                  CPU

                   │

       ┌───────────┼───────────┐

       │           │           │

      ALU      MEMORY UNIT   CONTROL UNIT

3. MEMORY OR STORAGE UNIT

The Memory Unit stores data, instructions, and intermediate results. It supplies information to other units of the computer whenever required.

It is also known as:

• Internal Storage
• Main Memory
• Primary Storage

Memory size affects the speed, power, and overall capability of a computer.

Computer memory is broadly classified into:

                 COMPUTER MEMORY

                       │

          ┌────────────┴────────────┐

          │                         │

    PRIMARY MEMORY             SECONDARY MEMORY

Functions of the Memory Unit

• Stores data and instructions required for processing.
• Stores intermediate results during processing.
• Stores final results before they are sent to an output device.
• Acts as a medium through which input and output information is transmitted.

4. CONTROL UNIT (CU)

The Control Unit controls and coordinates the operations of all parts of the computer. However, it does not perform actual data-processing operations itself.

Functions of the Control Unit

• Controls the transfer of data and instructions between different units of the computer.
• Manages and coordinates all the units of the computer.
• Obtains instructions from memory, interprets them, and directs the operation of the computer.
• Communicates with input and output devices for the transfer of data and results.
• Controls the overall functioning of the computer.

Important: The Control Unit does not itself process or permanently store data.

5. ARITHMETIC LOGIC UNIT (ALU)

The Arithmetic Logic Unit (ALU) performs arithmetic and logical operations.

It consists of two main sections:

                 ALU

                  │

         ┌────────┴────────┐

         │                 │

  ARITHMETIC SECTION   LOGIC SECTION

A. Arithmetic Section

The Arithmetic Section performs mathematical operations such as:

• Addition
• Subtraction
• Multiplication
• Division

Complex calculations are performed through the repeated use of these basic arithmetic operations.

B. Logic Section

The Logic Section performs logical operations such as:

• Comparing
• Selecting
• Matching
• Merging data

6. OUTPUT UNIT

The Output Unit consists of devices through which the processed information is presented to the user.

It acts as a link between the computer and the user. Output devices convert the computer’s processed results into a form that can be understood by humans.

Examples:

• Monitor
• Printer
• Projector
• Plotter

1. Which of the following is considered the brain of the computer?

A. Monitor
B. CPU
C. Keyboard
D. Printer

Answer: B. CPU

2. The silicon chips used for data processing are called
 (A): RAM chips
 (B): ROM chips
 (C): Microprocessors
 (D): PROM chips

Investigator DH (Jan-2024)

Answer: (C)
Explanation: Microprocessors serve as the central processing units (CPUs) contained on single integrated circuits (silicon chips), executing the logic and processing data for the computer.

3. Which of the following is a major component of the CPU?

A. ALU
B. Monitor
C. Printer
D. Keyboard

Answer: A. ALU

4. The CPU consists mainly of:

A. ALU, Control Unit and Registers
B. RAM, ROM and Hard Disk
C. Keyboard, Mouse and Monitor
D. Printer, Scanner and Speaker

Answer: A. ALU, Control Unit and Registers

5. ALU stands for:

A. Arithmetic Logic Unit
B. Arithmetic Language Unit
C. Application Logic Unit
D. Advanced Logic Unit

Answer: A. Arithmetic Logic Unit

6. Which unit performs arithmetic and logical operations?

A. Control Unit
B. Memory Unit
C. ALU
D. Input Unit

Answer: C. ALU

7. Which of the following is an arithmetic operation?

A. Addition
B. Comparison
C. Selection
D. Matching

Answer: A. Addition

8. Which unit controls and coordinates all the operations of a computer?

A. ALU
B. Control Unit
C. Memory Unit
D. Output Unit

Answer: B. Control Unit

9. The Control Unit:

A. Performs only calculations
B. Controls and coordinates the operations of the computer
C. Prints documents
D. Stores data permanently

Answer: B. Controls and coordinates the operations of the computer

10. Which unit stores data, instructions and intermediate results?

A. Memory Unit
B. Control Unit
C. Output Unit
D. ALU

Answer: A. Memory Unit

11. Which unit accepts data and instructions from the user?

A. Input Unit
B. Output Unit
C. Control Unit
D. ALU

Answer: A. Input Unit

12. Which unit presents the processed results to the user?

A. Input Unit
B. Output Unit
C. Memory Unit
D. Control Unit

Answer: B. Output Unit

13. Which of the following is an input device?

A. Monitor
B. Printer
C. Keyboard
D. Speaker

Answer: C. Keyboard

14. Which of the following is an output device?

A. Mouse
B. Scanner
C. Keyboard
D. Monitor

Answer: D. Monitor

15. The basic working cycle of a computer is:

A. Input → Processing → Output
B. Output → Input → Processing
C. Processing → Input → Output
D. Input → Output → Processing

Answer: A. Input → Processing → Output

16. Which component processes the data entered into a computer?

A. CPU
B. Keyboard
C. Monitor
D. Printer

Answer: A. CPU

17. Which of the following is responsible for performing logical operations such as comparison?

A. Arithmetic Section of ALU
B. Logic Section of ALU
C. Control Unit
D. Memory Unit

Answer: B. Logic Section of ALU

18. Which of the following is NOT a component of the CPU?

A. ALU
B. Control Unit
C. Register
D. Printer

Answer: D. Printer

19. Registers are:

A. Large external storage devices
B. Small and fast storage locations inside the CPU
C. Output devices
D. Input devices

Answer: B. Small and fast storage locations inside the CPU

20. Which of the following is used to store intermediate results during processing?

A. Memory Unit
B. Monitor
C. Keyboard
D. Printer

Answer: A. Memory Unit

21. The physical parts of a computer are called:

A. Software
B. Hardware
C. Firmware
D. Programs

Answer: B. Hardware

22. A set of instructions that tells a computer what to do is called:

A. Hardware
B. Software
C. Device
D. Data

Answer: B. Software

23. Which of the following is hardware?

A. MS Word
B. Windows
C. Keyboard
D. Antivirus Program

Answer: C. Keyboard

24. Which of the following is software?

A. Monitor
B. Keyboard
C. Mouse
D. Operating System

Answer: D. Operating System

25. The main components of a computer system are:

A. Hardware and Software
B. Keyboard and Mouse
C. Monitor and Printer
D. CPU and Keyboard only

Answer: A. Hardware and Software

26. Which component acts as an interface between the user and the computer for entering data?

A. Input Unit
B. Output Unit
C. CPU
D. Memory Unit

Answer: A. Input Unit

27. Which component acts as an interface between the computer and the user for presenting results?

A. Input Unit
B. Output Unit
C. Control Unit
D. ALU

Answer: B. Output Unit

28. The data and instructions required for processing are stored in:

A. Memory Unit
B. Output Unit
C. Keyboard
D. Printer

Answer: A. Memory Unit

29. Which of the following is responsible for directing the flow of instructions within the computer?

A. ALU
B. Control Unit
C. RAM
D. Output Unit

Answer: B. Control Unit

30. Which of the following correctly represents the flow of data in a computer?

A. Output → Input → Processing
B. Input → Processing → Output
C. Processing → Output → Input
D. Input → Output → Storage only

Answer: B. Input → Processing → Output

31. Which of the following memories is termed as the working memory of the computer?
A. RAM
B. ROM
C. Cache
D. None of the Above

Liaison Officer (LO) 2025

Answer: (A)

32. The full form of CPU is?

Which of the following correctly represents the flow of data in a computer?

A. Central Processing Unit
B. Central Processing User
C. Computer Processing User
D. Computer Processing Unit

HD(MPSC) 2023