Classification of computer hardware and their functions

Computer hardware is the physical tangible part of a computer. They comprise the main part of a computer both internal and external or peripherals. The main characteristic of hardware is it can be seen, felt, and even touch, unlike computer software.

The computer hardware is categorized into input, processing, storage, output, and communication devices. Each category is used for different functions. Input devices are used to enter data into the computer, then the processing component takes over to process it into information. During processing, it is stored in the main memory and secondary storage for future reference. To display the data being processed or results output devices are used and it can be shared with help of communication components.

computer hardware system showing processor, hard disk, keyboard, mouse and speaker

Functions of computer hardware devices

A computer is made up of many physical hardware components that are meant to achieve different functionality within the system.  It should be noted that all hardware work together in a harmonized way to achieve the main function of a computer which is data processing

Below we discuss the general function of hardware according to their classification.

  1. Keying and entering data into the computer. This is done by the input devices such as the keyboard, and document scanner among other devices.
  2. Processing hardware is used to process data after it has been entered. The hardware involved in data processing includes a computer central processing unit and main memory for temporal storage.
  3. Hardware such as hard disks and flash memories are used for storing data for future use.
  4. After data has been processed it is presented to the user as a hard or soft copy. Computer monitors are used for soft copies while printers are used to produce hard copies of data.
  5. Computer hardware is used to communicate data from one device to another by use of communication devices such as MODEM, and network cards.
  6. The computer power supply ensures all components get electric power to run.
  7. Fans, heat sinks, and cooling systems are used to cool down other components to the required temperatures.

Categories of computer hardware

1. Input hardware

Inputting of data involves entering data into a computer either by keying in, scanning, or using any other inputting methods. Input devices enable this to happen by providing the interface. Example of input device includes :

Mouse: It is a pointing device that when moved moves the cursor on the computer monitor. It is mostly used in computers with Graphical User Interface (GUI). You can read a more detailed article on the parts, and functions of the mouse.

Keyboard: It has keys like in a typewriter and it is used to key in the characters into the computer. It has different keys for different functions. Check on the types of keys found on the keyboard and their functions.

Joystick: It is a stick-like device that is used to control the movement of the cursor on the monitor to make a move in the game. As you move it there is an equivalent move on the game you are playing.

Scanners: They are used to convert the hardcopy to a softcopy to be processed by computer. If you want to edit a book you can use a scanner to convert it to an editable version. Since it captures the exact image it ends up reducing the error which may be brought about by typing the text. For a more detailed article on types of document scanners and how they work click the link.

2. Processing devices

When data is entered into the computer the next step is to manipulate it to get the information out of it. The processing hardware does that. They transform data entered into information. The Central Processing Unit (CPU) is concerned with that and it is made up of the following:

Control Unit (CU): It controls all the operations that happen in the computer and specifically the CPU. It has a clock that times what is supposed to happen when depending on it important.

Arithmetic Logic Unit (ALU): It is tasked with the role of carrying out the arithmetic (addition, subtraction, division, and multiplication) and logic operations (AND, NOT, OR etc). It does all the main calculations.

Main memory (RAM): It is a volatile (when the power goes off the content is lost) type of storage. When any process is being handled by the processor it is placed in the main memory. This increase the operation of the computer because retrieving data from the main memory is faster than the secondary memory.

3. Storage devices

When the data is entered into the computer it requires to be stored so that it can be processed (temporally) or for later use (permanently). Storage devices can either be categorized in terms of where they are found i.e. internal and external storage devices or how they are used, primary, secondary, and cloud storage.

Internal we have Random Access Memory (RAM), Read Only Memory (ROM), and Hard-disk drive while external are CD/DVD/Blu-ray, external hard disk, memory card, Flash disk memory, etc.

Primary storage devices are Random Access Memory (RAM) and Read Only Memory (ROM) while secondary devices are hard disk drives, CD/DVD/Blu-ray, flash disks, magnetic tapes, etc.

Cloud storage is a new technology of storing information. Data is stored in a remote server that is over the internet and can be accessed from anywhere at any time. Companies like Google offer Google cloud storage

4. Output devices

Outputting means disseminating the information to the audience. When data is analyzed and information is generated it needs to be given out, which is the main work of output devices. They give users an option to view what the processing devices are doing.

Output can either be produced in softcopy, hardcopy, or sound. Hardcopy output devices are printers, plotters, etc. The main softcopy output device is the monitor Video Display Unit (VDU) which comes in different technologies. The speaker is used to output sound information from the computer.

5. Communication devices

These are components that are used when you need to move data from one device to another using a network. Components such as MODEMs, WIFI, and network cards (NICs) are used to move data over the network. With the advancement of internet technologies and speed, most computing devices can send and receive data over the network.


These are other devices that can be attached to the computer through computer connection ports. They can include any of the 5 discussed devices.