chapter 2 Central Processing Unit cpu class 5

 

Every computer is made of hardware and software. The mechanical parts of a computer are called hardware. And the organized collection of data and instructions in the computer is called software.

FUNCTIONAL UNITS OF COMPUTER

Different hardware units of a computer help it perform specific functions. Let us take up the functions of the computer system one by one.

Input

The process of entering data, instructions and programs into the computer system is called input. Some common input devices are keyboard, mouse, microphone, joystick, light pen, etc. The input is processed by the computer in a systematic manner.

➤ Storage

Since the computer processes the data provided by us at a very high speed, it is necessary that we provide the data to it at the same speed. For this purpose, the data is stored in the system at a particular allotted space for faster access and processing.

➤ Arithmetic and Logical Processing

The instructions (given along with the data) are sent to the storage unit. The Arithmetic and Logic processor accesses the data stored in the storage unit and performs the required processing in the form of arithmetic calculations and logical operations. The result is again sent to the storage unit.

➤Output

The result, after processing, is stored in the storage unit before changing it to user-readable form. It is then displayed on the output devices such as monitor or visual display unit (VDU), and can also be obtained on paper using a printer.

➤ Control

All the above listed tasks performed by different parts of the computer are well-coordinated and controlled inside the computer system.

The function of arithmetic and logical processing as well as controlling and coordinating is jointly performed by the Central Processing Unit (CPU) or simply the processor of the computer.

The following diagram shows how different units of a computer take care of all its functions.

 

 

CENTRAL PROCESSING UNIT (CPU)

CPU is a small hardware component of a computer system fitted inside the CPU cabinet or the CPU box. In large machines, CPUs require one or more printed circuit boards (PCBs). PCBs are thin plates on which electronic chips and other electronic components are soldered. In personal computer and small workstations, the CPU is housed in a single postage-stamp sized silicon chip called microprocessor. This chip is also called an integrated circuit. Modern CPUs are small and rectangular structures with multiple metallic pins on their underside. They are directly inserted into the socket provided on the motherboard with the help of the pins. Intel and AMD (Advanced Micro Devices) are two popular CPU microprocessor manufacturing companies.

Do You Know?

CPUs are of different types and each type comes with varying degrees of speed, memory and pre-set instructions. The larger the CPU, the faster it can process, store and execute commands.

• A single-core CPU is the smallest unit available. It is usually found in smaller devices that only perform a simple set of actions such as a remote control or toy.

• Dual-core CPUs contain two command units and have enough power and memory for most personal computers.

• Multi-core CPUs contain multiple command units. They are mainly used by large industrial electronic devices, servers and network workstations.

Practice Time

Search the Internet for 'The history of development of the CPU'.

Draw a schematic diagram to show the functional units of a computer.

➤ Functional Units of CPU

In the previous section, you have learnt about the functional units of computer. Let us now learn about the functional units of CPU.

The CPU has three main functional units:

Control Unit (CU)

Arithmetic Logic Unit (ALU)

Registers

Control Unit (CU)

The control unit of the CPU is the controller and coordinator, in short, the supervisor of the whole computer.

The control unit controls the sequence of instructions and programs to be executed.

It controls the flow of information between the ALU and the Registers.

It coordinates the functions of all parts of the computer.

Arithmetic Logic Unit (ALU)

The actual processing of the data as per instructions is done by this unit of the CPU.

It performs all mathematical calculations like addition, subtraction, multiplication and division.

It performs logical operations like comparisons such as greater than (>), less than (<), equal to (=), etc.

This is a small memory unit on the CPU.

The data is stored here while it waits to be processed. The ALU can then easily access this data for its calculations.

It helps to easily and quickly get information stored in the computer memory.

It helps the CU to quickly transfer data to other parts of the computer.

 

Do You Know?

The clock rate is the speed at which a microprocessor executes instructions. Every computer contains an internal clock that regulates the rate at which the instructions are executed. The faster the clock, the more the instructions the CPU can execute per second. The rough measure of the speed of the CPU in following instructions is measured in MIPS (millions of instructions per second).

The Right Way

It is not advisable to open CPU box without the help of a technical expert. Moreover, the

arts inside it are very delicate and sensitive.

 

 

Let Us Recall

The five major functions of a computer system are input, storage, arithmetic and processing, output and control. Different devices perform these specific

functions The CPU controls, coordinates and executes all instructions, and is therefore relen to as the brain of the computer.

There are three main functional units of the CPU: the Control Unit (CU), the Arithmetic Logic Unit (ALU) and the Registers.

The CU is the supervisor of the CPU and the whole computer.

The ALU performs all the mathematical calculations and logical operations.

Registers is a small memory unit on the CPU where all data to be processed is store for easy and quick access by the ALU.

 

Exercises

A. Tick (✔) the correct option.

1. Which of the following is not a function of computer?

   (a) Controlling and coordinating

   (b) Making arithmetic calculations

   ✔ (c) Thinking and deciding

 

2. Which of the following body organs can CPU be compared to?

   (a) Liver

   ✔ (b) Brain

   (c) Backbone

 

3. What is the full form of VDU?

   (a) Versatile Display Unit

   ✔ (b) Visual Display Unit

   (c) Volatile Display Unit

 

4. Which among the following is the odd one?

   ✔ (a) ALU

   (b) CU

   (c) Keyboard

 

B.Write the full form of each of the following:

1. CPU stands for **Central Processing Unit**. It is the brain of the computer that performs all the basic logical and arithmetic operations

2. CU stands for **Control Unit**. It is a main component of the CPU that directs the operations of the processor

3. ALU stands for **Arithmetic Logic Unit**. It is a significant part of the CPU responsible for all numerical and logical functions

C. Fill in the blanks.

1. Devices such as keyboard, mouse, joystick and microphone are called input devices.

 

2. The flow of information between ALU and Registers is controlled by the Control Unit (CU).

 

3. The Arithmetic Logic Unit (ALU) unit of CPU performs mathematical and logical operations.

 

4. The instructions given as input are first stored at the storage unit before getting processed.

 

5. In personal computers, CPU is housed in a single chip called a microprocessor.

 

D. Write the main functions of each of the following.

 Main Functions of Computer Components (Simple Version)

 

 1. Central Processing Unit (CPU)

 

       I.            Executes instructions and performs calculations

    II.            Coordinates the flow of data and instructions

 III.            Controls the overall operation of the computer

 

 2. Control Unit (CU)

 

                   I.            Fetches and decodes instructions

                II.            Manages the sequence of operations

             III.            Directs the flow of data and instructions

 3. Arithmetic Logic Unit (ALU)

i.       Performs arithmetic operations

ii.     Performs logical operations

iii.  Executes instructions from the Control Unit

 

 4. Registers

 

i.       Temporarily stores data and addresses

ii.     Provides fast access to information

iii.  Enables efficient data transferF.

 

Answer the following questions.

1.    Why is CPU called the brain of the computer?

 

The CPU is often referred to as the "brain" of a computer because it performs most of the calculations and data processing required to execute instructions from computer programs. It is responsible for carrying out the basic arithmetic, logic, and control operations that are essential for the functioning of a computer. Like the human brain, the CPU manages the timing of each operation and carries out instructions or commands from applications or the operating system.

 

2.    What is the role of Registers in a CPU?

 

Registers play an important role in the CPU by temporarily storing data, addresses, and intermediate results required for the CPU's operations. They provide fast access to information needed by the ALU and Control Unit, enabling efficient data transfer between the CPU, memory, and other components. The CPU features a number of registers that are used to store operands, addresses, and other information needed for calculations. Data transfer between registers and memory is controlled by the CPU.