Block Diagram of Computer System and its Components & Functions!!

Hi, friends! Today, we are going to explain simple block diagram of computer and its components.

In this article, we will explore you in detail a block diagram of computer and explain its components!

After reading this post carefully, you will completely aware about all functional a block diagram of computer system!

Explain Block Diagram of Computer

A block diagram of computer displays the internal structure of the computer, as we as the block diagram provides the quick overview of internal working work flow of computer system from inserting data to retrieving the desired output.

Computer system performs all their tasks as block-wise so it is known as ‘Block Diagram of Computer‘.

Computer is an electronic device; and it is capable to perform logically and mathematically operations at the higher speed. Computer system executes these mathematically operations on few data or information, and this data is served by the users with helping of input devices otherwise these data is produced for its own operation. A computer has ability to execute all data that is made from several functional units that perform few certain tasks.

The functional units of the computer are proper designed in the block diagram of the computer. A computer splits the own tasks among these major functional unit that are shown in the block diagram of the computer system.

Block Diagram of Computer Tutorial Headlines:

In this section, we will show you all headlines about this entire article; you can check them as your choice; below shown all:

  1. Explain Block Diagram of Computer
  2. Simple Block Diagram of Computer System
  3. Block Diagram of Computer and its Components
  • Input Unit
  • Central Processing Unit
  • ALU – Arithmetic Logic Unit
  • CU – Control Unit
  • Memory Unit
  • Primary memory
  • Secondary memory
  • Output Unit
  1. FAQs (Frequently Asked Questions)
  • What is block diagram of computer?
  • How many blocks does a computer have?
  • What are the components of block diagram of computer system?
  • What is computer block diagram and explain its components?

Let’s Get Started!!

Simple Block Diagram of Computer System

Here, we will draw the block diagram of computer system and label it with neat a clean


Block Diagram of Computer and its Components

Computer system performs all tasks along with the combination of major four components, Therefore here we will cover all possible things about components of block diagram of computer system along with their functions; below shown all things step by steps, you can read them:

  • Input Unit
  • Central Processing Unit
    • ALU – Arithmetic Logic Unit
    • CU – Control Unit
  • Memory Unit
    • Primary memory
    • Secondary memory
  • Output Unit

Input Unit

Input Unit contains the input devices like as scanner, joystick, keyboard, mouse, etc. These input devices allow to user for inserting the instruction or information into the computer system. Input unit plays the role as a mediator of communication that gets the data from user to the computer system for organized manner for processing.

Input Unit functions are

  • Computer receives the data through input devices like as mouse, keyboard, and joystick and so on.
  • The input unit helps to convert the inputted instructions into machine-readable (0’s and 1’s) for later processing.

Central Processing Unit

CPU (Central Processing Unit) is also called the “Brain” or “Heart” of the computer system. CPU is a hardware electronic device that is capable to perform various types of operations like as arithmetic and logical operation. It has ability to perform all calculations, comparisons or operations inside of the CPU.

CPU functions are

  • Fetch all instructions from memory
  • Handle the sequence of all instruction
  • To make communication in between all peripheral devices
  • Handle the flow of all data and instructions from one component to other.
  • To able to perform computation needed as per the application program.

Central Processing Unit has two segments like as arithmetic logic unit and control unit.

Arithmetic and Logic Unit

ALU (Arithmetic logic unit) has responsible to perform all arithmetic and logic operations, which are data inserted via input devices, is stored in the main memory storage unit.

Arithmetical Unit can handle few simple operations like as addition, subtraction, division, and   multiplication.

Logical Unit is capable to control the logical operations like as AND, OR, EQUAL, GREATER THAN, and LESS THAN, and so on.

Other operations like as comparing, selecting, matching, and merging data are also performed by Logical Unit.

Logical Unit is also able to perform Bit-shifting operations like as left shift is represented by the << operator and the right shift is represented by the >> operator.

Control Unit

The control unit (CU) deals to perform all activities and operations of computer inside the CPU. Control unit has a responsible to control input/output, memory, and other devices which are linked to CPU.

Control unit obtains the set of instructions or information, then it helps to convert the instruction set to control signals, then these signals are moved to central processor for later processing. CU is able to understand which types of operations to execute with accurately. The control signals are getting to help as per the prioritizing and scheduling the activates. It allows to make coordination all task inside computer in syn along with input and output units.

Control Unit Functions are

  • It gives to instruct the input unit, where to save data, when input unit obtains it from the user through few input devices.
  • Control unit can read one instruction at a time while executing of a program, and then it helps to execute all instruction at the ALU.
  • The output of execution ALU delivers after the calculation is hand over to control unit that direct it move to memory and also to output unit for seeing the output on the screen.

Memory Unit

Memory unit also plays the major role in the computer system because it helps to store data and instructions before and after processing. This unit transfers the set of instructions to another unit of system as per the need.

Memory Unit is divided into two categories like as –

Primary Memory:  Primary memory is known as “Main Memory” or “Internal Memory” or “Primary Storage Device” or “Internal Storage Device” as well as they play vital role in computer, because those memories are capable to access all data directly from CPU with the help of various buses. These memories have limited capacity for storage and made by integrated circuits (IC) or semiconductor components.

Primary storage devices are available in two variance such as volatile and non volatile. Volatile memory is called temporary memory because all data deleted when power get turn off mode but its access time and response time much fine to secondary memory. Non volatile memory is permanent memory in which nothing data erase when system is turn off.

Types of Primary Memory


Registers are included in the CPU. They have low capacity for storing the instructions, and data only on before and after processing mode.

Cache Memory

This cache memory has higher speed for accessing data, and allows to computer for storing piece of data in temporary nature. Cache memory is place at near the CPU and RAM. Cache memory speed is very fast because its travel distance is short between RAM to Cache memory. There are three types of Cache memory such as – Level 1 cache, Level 2 cache, Level 3 cache.



RAM is primary memory and RAM stands for “Random Access Memory“. Ram is capable to access any data randomly any time as well as from any location to computer. This is volatile storage memory means to temporary memory in nature, because entire data goes delete while computer get turn off mode. RAM regains all data from CPU in run-time and sends to control unit, and it is a fastest memory to hard disk.

RAM Types are:

Static RAM

Static RAM is also volatile primary memory, and it made by flipflop. Static Ram works in computer as a form of Cache Memory, but it consumes more power as well as more costly to DRAM. In Static RAM uses six transistors, and each transistor use for one bit.

Dynamic RAM

Dynamic RAM is other types of RAM, and volatile also in nature. In which use the capacitors for storing data in few milliseconds when power turn on. Dynamic RAM has slow speed as well as consume low power but has capable to store more data compare to SRAM. DRAM is cost effective as well.


ROM is primary memory and ROM stands for “Read Only Memory”. This memory is able to store data in permanently means to have non-volatile in nature. ROM is programmable chip because in which stored all instructions that are most required when to start computer. This process is known as “Bootstrap”. ROM is not limited for computer because these chips use in other equipment like as washing machine and microwave as well.

 There are four types of ROM such as:


MROM stands for “Masked ROM“.  MROM has to contain the all pre-planned programs like as piece of instructions, and cheaper as well.


PROM Stands for “Programmable Read Only Memory“. Users can store any data as per their requirement because these ROM is available in market in blank. But in which store instructions (programs) only one time because after filling programs it cannot delete.


EPROM Stands for “Erasable and Programmable“. In these types of ROM, users have power to editing (erase) the stored instruction (program) in EPROM. EPROM is erasable by ultra-violet light for some time like as 40 minutes.


EEPROM Stands for “Electrically Erasable and Programmable Read Only Memory“. In EEPROM, all activities such as programming and erasing are performed by electrically. This EEPROM is able to reprogrammed and erased in more than ten thousand time. Entire chip cannot be erased one time, only erase one byte at once.

Secondary Memory: Secondary Memory is also called “storage device” and “auxiliary memory“, “external memory“. Secondary storage devices are volatile in nature, it means that data does not discard while power turn-off, in which all data store for long time. Secondary memory has the speed of access of data is very slow compare to primary memory, and cheaper as well. Without primary memory, those secondary storage devices are useless because for processing the secondary memory must be needed the primary memory, first of all data are transferred into primary memory then these data make for executable.

Types of Secondary Memory

There are four types of secondary memory; below shown all, you can check them!

Magnetic Storage Devices

In the Magnetic storage devices, all data are stored with using magnetized medium, and those types of data saved in that medium in the binary form like as 0 and 1. This magnetic storage has also non-volatile storage nature. Today’s, mostly people are preferred to magnetic medium because on the magnetic storage devices can be performed read/write activities very easily. Magnetic storage devices have huge capacities for storing data that it’s more attractive point. These storage devices are not more costly but their data accessing power is slow, but this magnetic mechanism also to be used in the RAM that have good data accessing power to other.

Optical Storage Devices

In the optical storage devices, all read and write activities are performed by light. All recording information stores at an optical disk. As per the opinions of data scientist that compact space is most useful for huge data storage. Their big advantages are not more costly, light weight, and easy to transport because it is removable device unlike hard drive.

Flash Memory Devices

Flash Memory was introduced by Dr. Fujio Masuoka in 1980. Flash memory is also known as electronically erasable programmable read only memory (EEPROM), because in which piece of  code like as programming can be write and erased by electrically. Flash memory also uses for the storing data to computers as well as electronic devices such as USB flash drives, MP3 players, digital cameras and solid-state drives. Flash memory is non volatile in nature because all data are persisted in the memory when power is turn-off.

Online Cloud System

Clouding is systematically model for storing data in computer, and in which entire data are stored in logically nature. Those clouding system are managed by other hosting companies. With the help of online clouding, all data can be access by couples of users anytime and anywhere. Big advantages are not place limitation as well as no need carry any storage device.

Output Unit

The output unit of the computer system delivers the results of computation and displaying the output outside the world. The output unit generally works as the opposite process of the input unit and it convert the binary language digitalized information to electronic impulses, which are readable to the output devices. There are few output devices, which are commonly used like as monitor, projector, headphone, speaker, etc.

Output unit provides the result into two forms like as soft copy or hard copy. The monitor is used for soft copy as displaying on the screen, whereas printer is used for hard copy as displaying on the paper.

Output Unit functions are

  • Output Unit receives the data or information into machine language from the primary memory of computer system.
  • Output Unit helps to convert the machine language into human – understandable.

FAQs (Frequently Asked Questions)

What is block diagram of computer?

Block diagram of computer is a blueprint that represents the internal structure of computer system, as well as showing overview of internal working flowchart of computer system.

How many blocks does a computer have?

There are major four blocks in the computer system like as Input Unit, Central Processing Unit, Memory Unit, and Output Unit. And further these blocks are divided into their instruction. Already we have shown all blocks above in this article, you can read them.

What are the components of block diagram of computer system?

There are four main components of block diagram of computer that this article will cover: input devices, processing devices, output devices and memory (storage) devices.

What is computer block diagram and explain its components?

Through this post, we have been covered in detail about a computer block diagram and its component along with their functions; you can prefer this blog post be careful!


I hope that through this article, we have completely educated about a block diagram of computer system and its components along with function with ease. If this blog post is helpful for you, then please share it along with your friends, family members or relatives over social media platforms like as Facebook, Instagram, Linked In, Twitter, and more.

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