Types of Computer Hardware

What is a computer system?

We all know that Computers are machines built with different materials such as metal and plastic. But how does it work, interact and function as a productivity tool.

A computer system consists of software and hardware components that work together. The Input devices, Output devices, and the Central Processing Unit which is also called the CPU are basically considered as computer hardware while the software is a set of instructions that can be stored and run by hardware.

In this article, we will discuss about Hardware components in detail and how they function. Out next article will be on computer software and we suggest you should go through it to understand a computer system thoroughly.

Data Processing cycle

Generally, computers follow the Input > Process > Output cycle. Computers accept Input (using Input devices), process it (using Central Processing Unit), and produce an output as a result (using Output devices).

The following shows an overview of the Data Processing Cycle. The most popular Input devices are Keyboard and the Mouse whilst Monitor and Printers are popular Output devices.

Input (Keyboard, Mouse, etc) – may be data or instructions
Processing (CPU) – input is then processed or manipulated into meaningful information
Output (Monitor, Printer, etc) – the results are then displayed through an output device using a human-readable form.

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Hardware components of a computer system

Various Hardware components that make up a computer system can be classified into three categoroes.

  • Input devices
  • Components inside the CPU
  • Output devices

Let’s dive into these details to learn what they are and how they function to make the Computer system.

Input Devices

Computers accept data and instructions using Input devices.

List of Computer Input Devices

There are many Input devices today and the Keyboard, Mouse, Scanners, Camera are very popular nowadays.

The following table shows a list of Input Devices.


An Input device used to change the position of the cursor or any other object on the screen. More popularly used for playing video games.

Light Pen

A light pen is a computer input device in the form of a light-sensitive wand used in conjunction with a computer’s cathode-ray tube (CRT) display.

Image Credit to Original Owner


Used to input sound into a computer. It records your voice or other sounds.

Graphic Tablet

an Input device used to draw images and pictures on a screen. It consists of a flat surface on which a user can draw using a pen-like drawing device called Stylus. Great for capturing handwritten notes and signatures.

Barcode Reader

An Input device used to read Barcodes. A Barcode is a special pattern printed in lines of different thickness. A Barcode reader interprets these lines to input the information into a computer.

Image Credit to Original Owner

Touch Screen

A touch-sensitive computer display screen. It identifies the presence and the position within the display region. They are very easy to use and found in public places such ATMs, Airports, etc.

Magnetic Ink Character Recognition (MICR)

A special device used to process checks in banks. The number codes at the bottom of the checks are written using a special ink called Magnetic Ink.

Output Devices

An Output device produces an output in user-readable form.

List of Computer Output Devices

The Output devices such as the Computer Screen, Speakers, Printer are very popular nowadays.

The following table shows a list of Output Devices.

Computer Printers

A Printer is a device used to print characters and images you see on the screen as an output in a paper or transparencies. 

The output of the printer is a permanant readable form is known as the hard copy.

Printers can be classified in to two broad categoroes.

  • Impact Printers
  • Non-Impact Printers

Impact Printers

These type of Prinetrs make a strike on paper using a print-head or a needle as against the Printer ribbon.

These printers are comparatively slow, noisy and low in quality. Mainly used for printing bills or documents with characters and simplelines.

Dot-Matrix Printers

Dot Matrix Printers are also called Impact Matrix Printer. These are one of the first models of computer printer that involves print head running in back and forth motion or horizontally across the page and prints mainly by impact of pins striking the paper through an ink ribbon cable forming bunch of dots (dots per Inch or DPI) for printing each letter.

For example Epson LQ 2190

Classification of Dot-Matrix Printers

Dot Matrix Printers can be classified by different features such as :

  • printing directions,
  • number of pins or dots used per letter,
  • based on the movement of print head and
  • Print color

Classification of Dot-Matrix Printers by Print Direction

Based on printing directions, Dot matrix printers are classified into two types namely, unidirectional and bidirectional printers.

A unidirectional printer prints only in one direction i.e., from left to right whereas, a bi-directional printer prints in both the directions – from left to right & right to left.

Classification of Dot-Matrix Printers according to number of pins or dots used per letter

According to number of pins or dots used per letter, there are mainly 3 types of printers – 9 pin, 18 pin and 24 pin.

Classification of Dot-Matrix Printers based on the movement of print head

There is 80 column printers and 132 column printers. In these two types of printers, the print head moves 80 columns and 132 columns respectively.

Classification of Dot-Matrix Printers based on the Print Color

According to this classification there are monochrome printers and color printers. Monochrome printers print only one color (black) and color dot matrix printers are made to print a maximum of 4 colors – i.e. Red, Green, Blue and Black.

Classification Sumamry of Dot-Matrix Printers

Non-Impact Printers

On the other hand, Non-Impact Printers do not stike the Print-head against the Ribbon. Non-Impact Printers may use Ink or Laser beams.

These prinetrs therefore make less noise, faster and produce high quality output.

Laser Printers

Laser printing is an electrostatic digital printing process. It produces high-quality text and graphics at a high speed.

For example HP Laser MFP 135a Printer

Ink-Jet Printers

Inkjet printing is a type of computer printing that recreates a digital image by propelling droplets of ink onto paper and plastic substrates. Inkjet printers are the most commonly used type of printer, and range from small inexpensive consumer models to expensive professional machines.

For example a modern HP Deskjet All in One Inkjet Printer

Image Credit to Original Owner


A Plotter is special type of printer used to produce high quality graphs, diagrams, sketches, etc. Plotters are mainly used by Engineers, Architects and Map-Makers to print plans (buildings, bridges), diagrams (machines) and large-scale maps.

HP A0 Plotter 7585B

Image Credit to original Owner

The Components of Central Processing Unit (CPU)

There are various hardware components present inside the Central Processing Unit (CPU) box. That includes but not limited to:

  • Motherboard (mobo)
  • Switched mode Power Supply (SMPS)
  • Basic Input Output System (BIOS)
  • Primary Memory – Random Access Memory, Read Only Memory, etc
  • Secondary Memory – Hard disk Drive, CD-ROM, etc

Computer Motherboard (mobo)

The Main Board that holds many of the crucial components of a computer system is called a Mother board. It allows all components to receive power enable communication with eachother.

The Motherboard mainly holdes the Processor or the Microchip, Memory Chips and several cards such as Audio and video card.

Computer Processor or CPU

The Processor is the brain of the computer system which is present on the Motherboard and controls all the components. The Processor accepts data and instructionss through Input devices, process it and output results through Output devices.

Switched Mode Power Supply (SMPS)

The SMPS convert the main power supply into propper voltage required by each components. Besides the Processor SMPS plays a vital role within the entire computer system.

Computer Ports

Despite all components, computer Ports reside inside the CPU box and supports communication between each components to talk to eachother.  These ports allows you to plug varioud devices such as the Keyboard, Mouse or Printer. Nowadays almost all devices uses the popular USB (Universal Serial bus) Ports.

The Primary Memory Types

We wrote a detailed article about the The Types of Computer Memory if you like to read.

Random Access Memory (RAM)

The data and instructions can be written onto and read from RAM. Therefore RAM is known as the read/write memory.

When a computer is switched ON, the Operating system is loaded into RAM. When you start working on any application, it is loaded into RAM and we actually working on this copy.

RAM is also called Volatile Memory. It means It will retain data as long as the electricity is available (or the computer is ON).

The size of the RAM of any Computer affects its processing capability. That means, if the RAM is high it can load more applications and capable of processing them in the memory. It also affects the multi-tasking capabilities (We will discuss multi-tasking in a separate article).

Read-Only Memory (ROM)

ROM is, on the other hand, a type of permanent memory. The Computer Memory in ROM is pre-recorded and it cannot be erased (There are ways to erase this memory but not by you and me). Therefore, it is called a non-volatile memory as it retains in Memory even after the electricity is cut-off.

The ROM is used to store a special program called the BIOS (Basic Input Output System). The BIOS software in the ROM is used to load the Operating system. Without ROM, we cannot load the Operating system, and therefore, we cannot do any work on the computer.

Erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM) and flash memory can be erased and re-programmed.

The Secondary Memory Types

The Secondary memory is also called auxiliary Memory, External Memory or Backup Memory. The Primary Memory has a limited storage capacity and not capable of storing data permanantly. This is the reason why you need to use a Secondary Memory or storage devices.

Hard Disk (HD)

The Hard disk is a primary type of non-volatile memory used to store your data on a computer. It can store large amounts of data and can reside inside the computer or additionally outside as well (External Hard disk).

Compact Disc (CD)

The CD is another form of non-volatile memory once widely used. It is portable and cheaper to use. Most of the software and games are preloaded into CDs due to its portability and durability.

There are two types of CDs;

  • CD-R – The “R” stands for Recordable. As its name implies, we can write data into these CDs. Once done, we cannot remove these data.
  • CD-RW – The “RW” stands for Re-writable. As its name implies, we can re-write data into these CDs multiple times.

There are devices called CD Writer which can be installed into your computer to write data into a CD. CDs have now become obsolete due to the invention of DVDs.

Digital Versatile Disc (DVD)

A DVD is very similar to its look but it is capable of storing six times of data stored in a CD. In addition, a DVD can be single-sided or double-sided increasing the capacity further. DVDs also have recordable and re-writeable types.

Sony Rewritable DVD

Blu-ray Disc

The name Blu-ray is derived from the blue-violet laser that used to read and write data. The Blu-ray disc is capable of storing 25GB data, that is five times the DVD is supported. Mainly used to store high-quality video and games which requires high capacity storage.

Front of an experimental 200 GB rewritable Blu-ray Disc

Flash Drive

A Flash drive is also generally called a Pen Drive, USB Drive, etc. This can be connected to the USB (Universal Serial Bus) port of the computer. This is similar to a Hard disk but portable and very smaller in size and less expensive. Once Flash drives were embedded into everyday tools such as key tags, pens, etc, and was popular among users.

Assortment of flash drives

Memory Card

A Memory Card is very smaller in size and used to store data in various electronic devices such as Digital cameras, smartphones, mp3 players, and many portable devices.

Miniaturization is evident in memory card creation; over time, the physical card sizes grow smaller.

Obsolete popular Secondary storage devices

They were popular devices called Floppy Disks once widely used in every computer. They were the first portable secondary memory commercially successful. They came in three different sizes, 8-inch, 5 14-inch, and 3 12-inch floppy disks.

8-inch, 5 1⁄4-inch, and 3 1⁄2-inch floppy disks

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Summary of Computer Hardware

We hope this article helped you learn about the Hardware components of a computer system.

Let’s recap the details.

  • Various Hardware components that make up a computer system can be classified into three categoroes.
    • Input devices
    • Components inside the CPU
    • Output devices
  • Computers accept data and instructions using Input devices.
  • An Output device produces an output in user-readable form.
  • Eexamples of Imput devices are Keyboard, Mouse, Scanner, Light Pen, Graphic Tablet, touch Screen, Microphone, Barcode Reader, Joy Stick, etc.
  • Examples of Output devices are Monitors, Printers, Speakers, Plotters, etc
  • The CPU boc holds various hardware components such as Motherboard, Processor, SMPS, Primary Memory, Secondary Memory, and Ports.
  • There are two types of Computer Memory (Primary Memory & Secondary Memory).
  • The Primary Memory can be further divided into Random-access Memory (RAM) and Read-Only Memory (ROM).
  • The Secondary Memory can be further divided into Hard disk (HD), compact disc (CD), Digital Versatile Disc (DVD), Blu-ray Disc, Flash Drive, External Memory Cards.

Read Previous: The Types of Computer Memory

Read Next: Types of Computer Software

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