1.3 Central Processing Unit (CPU)

 

1.3 Central Processing Unit (CPU)

The Central Processing Unit (CPU) is the brain of the computer system that controls all operations of the computer and processes data and instructions.

It is responsible for receiving data from the input unit, executing instructions provided by the user, and generating output information.

Intel CPUs (e.g., Intel Core i5, i7, i9), AMD CPUs (e.g., Ryzen series, EPYC), Apple CPUs(M1, M2), ARM CPUs ((e.g., Qualcomm Snapdragon, MediaTek)), etc. are popular examples of CPUs.

 

1.3.1 Function of the CPU

 

i. Fetching: Retrieves data and instructions from memory (RAM).

ii. Decoding: Interprets the instructions to understand required actions.

iii. Executing: Performs calculations, data movement, or hardware interaction.

iv. Storing: Stores results back into memory or sends them to output devices.

v. Managing Interrupts: Handles hardware and software interruptions to ensure smooth processing.

 

In short with Example (25 + 10):

·        Fetch → Get the problem from memory.

·        Decode → Understand it’s an addition.

·        Execute → Do 25 + 10 = 35.

·        Store → Save result (35) in memory to display.

·        Manage Interrupts → Handle side tasks (e.g., notifications).

 

Example (Working of CPU):

1. The CPU fetches instructions from memory.
2. The Control Unit decodes the instructions.
3. The Arithmetic Logic Unit executes the instructions.
4. The results are stored in registers or sent to memory/output devices.

📌 This is the fetch–decode–execute cycle.

 

1.3.2 Components of the CPU: Control Unit, Arithmetic and Logic Unit, and Memory Unit.

 

Control Unit (CU)

The Control Unit (CU) controls the working of all parts of the computer system. It controls the movement of data inside as well as outside the CPU. The CU communicates between the registers and the ALU and between the CPU and all input, output, and storage devices. It directs all parts of the computer system to perform their tasks.

 

Arithmetic Logic Unit (ALU)

The Arithmetic Logic Unit (ALU) performs all arithmetic and logical operations. Arithmetic operations include addition, subtraction, multiplication, and division. Logical operations include greater than, less than, and not equal comparisons.

 

Memory Unit (MU)

The Memory Unit (MU) stores data, instructions, and results required during processing. In the CPU, the Memory Unit mainly consists of registers, which are small, high-speed memory units. Registers store immediate data, instructions, and results while processing data.

 

Registers

Registers are small, fast memory units inside the CPU. They are used to store immediate data, instructions, and results temporarily during data processing.

The speed of a computer depends mainly on its microprocessor.

1. CPU stands for: ⭐

A. Central Program Unit                    B. Computer Processing Unit
C. Central Processing Unit ✅           D. Control Processing Unit

2. The CPU is also known as the: ⭐

A. Heart of the computer                    B. Memory of the computer
C. Brain of the computer ✅              D. Storage of the compute

3. Which unit performs arithmetic and logical operations? ⭐

A. Control Unit                       B. Memory Unit         C. Arithmetic Logic Unit ✅ D. Input Unit

4. Fetching refers to: ⭐

A. Performing calculations                                                    B. Storing results
C. Retrieving data and instructions from memory ✅           D. Sending output to devices

5. Which unit controls the movement of data inside and outside the CPU? ⭐

A. ALU                       B. Memory Unit                     C. Control Unit ✅     D. Register

6. Registers are:

A. Large storage devices                                                        B. Input devices
C. Small high-speed memory units inside CPU ✅               D. Output devices

7. Which function ensures smooth processing by handling interruptions? ⭐

A. Executing                           B. Storing                   C. Decoding    D. Managing interrupts ✅

8. The speed of a computer mainly depends on its: ⭐

A. Keyboard               B. Monitor                  C. Microprocessor ✅            D. Printer

9. Which of the following are examples of CPUs?

A. Intel, AMD, Apple, ARM ✅                    B. Mouse, Keyboard, Scanner
C. RAM, ROM, HDD                                     D. Printer, Monitor, Speaker

10. The CPU receives data from which unit? ⭐

A. Output unit                         B. Storage unit            C. Input unit ✅D. Control unit

11. Decoding in CPU means: ⭐

A. Performing calculations                            B. Translating instructions into machine language
C. Interpreting fetched instructions ✅         D. Storing results

12. Managing interrupts is done to ensure: ⭐

A. Faster typing                                                          B. Better storage        

C. Smooth and efficient processing ✅                     D. More memory

13. Registers are mainly used to store: ⭐

A. Permanent data                                                      B. Backup files          

C. Immediate data and instructions ✅                      D. Output information only

14. Which statement is CORRECT about the microprocessor? ⭐

A. It is an input device                                   B. It controls only output devices
C. It contains CU, ALU, and registers ✅     D. It stores data permanently

15. Which of the following tasks is performed during the execution stage? ⭐

A. Retrieving instructions from RAM                                    B. Interpreting instructions
C. Performing calculations and data movement ✅              D. Storing instructions permanently

 

Define Central Processing Unit (CPU).  Write any two examples of CPUs.

Explain the functions of the CPU.

Explain the components of the CPU.

Explain the working of the CPU.

Describe the Control Unit and Arithmetic Logic Unit.