BLOCK DIAGRAM OF COMPUTER

Block Diagram of Computer 

By: 

Dr. Vandana Jindal

A computer can process data, pictures, sound  and graphics. 

They can solve highly complicated problems  quickly and accurately. 

 A computer as shown in Fig. performs  basically five major computer operations or  functions irrespective of their size and make.

1. Input: This is the process of entering data and programs in to the computer system.  You should know that computer is an electronic machine like any other machine  which takes as inputs raw data and performs some processing giving out processed  data. Therefore, the input unit takes data from us to the computer in an organized  manner for processing. 

2. Storage: The process of saving data and instructions permanently is known as  storage. Data has to be fed into the system before the actual processing starts. It is  because the processing speed of Central Processing Unit (CPU) is so fast that the  data has to be provided to CPU with the same speed. Therefore the data is first  stored in the storage unit for faster access and processing. This storage unit or the  primary storage of the computer system is designed to do the above functionality.  It provides space for storing data and instructions. 

The storage unit performs the following major functions:  

• All data and instructions are stored here before and after processing.  • Intermediate results of processing are also stored here.  

3. Processing: The task of performing operations like arithmetic and logical operations  is called processing. The Central Processing Unit (CPU) takes data and instructions  from the storage unit and makes all sorts of calculations based on the instructions  given and the type of data provided. It is then sent back to the storage unit.

BLOCK DIAGRAM OF A COMPUTER: Computer contains five basic units 1) Memory Unit 

2) Arithmetic Logic Unit (ALU) 3) Input Unit 

4) Output Unit 

5) Control Unit (CU)

CENTRAL PROCESSING UNIT (CPU): •CPU is the brain of a computer. 

•Transform raw data into useful information. •CPU is responsible for all Processing. •It has two parts 

Arithmetic Logic Unit (ALU) Control Unit (CU)

Arithmetic Logic Unit (ALU): 

•It is the part where actual processing takes place. •It can perform Addition, Subtraction, Multiplication,  Division, Square Roots (etc) and logic operations such as  AND, OR (etc) on binary numbers. 

Control Unit (CU): 

•It tells the computer that, “What specific sequence of  operations it must perform”. 

•It also specifies timing of the instructions. 

•Its function is to Fetch, Decode and Execute instructions  that are stored in memory. 

•It controls

Memory Devices 

• Arithmetic Logic Unit 

• All Input/Output Devices 

Main Memory: 

• Also called Primary memory or Internal memory. • Memory is used to store data temporary or  permanently. 

• Data stored in memory can be used for required task. • RAM and ROM are most commonly used as main  memory.

• Data can Read/ Write randomly. 

• RAM is used for storage of active programs and  data. 

• It is a temporary memory. 

• It is also called Volatile memory (it will lose all  stored data if power is turned off). 

• It increases the processing speed of a computer. • RAM is available in different sizes. 

• Also known as Primary memory.

ROM (Read Only Memory): 

• It is a permanent memory. 

• Data can only Read. 

• It is also called Non-Volatile memory (it will not lose  stored data if power is turned off). 

• Instructions are stored on it during manufacturing. Types are 

• PROM (Programmable Read Only Memory) • EPROM (Erasable Programmable Read Only Memory)

Input Unit 

• Input unit is used to communicate with computer. • Input unit is used to feed Instructions/Commands in  computer. 

• These devices are often called as “Peripherals”, because  they are separated physically from CPU. 

• Input data Reads data from user, Converts it to machine  code (0 or 1) and then Store it into main memory. • Some common input devices are Mouse 

• Keyboard Joystick 

• Microphone 

• Scanner (etc).

Output Unit 

• These are also peripheral devices that transfer  data from main memory to user. 

• Output unit receives data from main memory  in binary form and converts it into user  readable form. 

• Some common output devices are Monitors • Printers Plotters Speaker 

• Fax Machine (etc).

 Thank you