Four Basic Functions of Computer Systems

The functions of computers are numerous as modern computers are capable of completing simple to complex tasks with ease. Computer technology and related devices or components are becoming more advanced over time. In this way, it is very difficult to classify the functions of a computer. However, some basic functions are performed by every computer system irrespective of its size, power, capability, or modernity.

In this article, we are discussing the basic functions of a computer. When discussing the basic 'functions of a computer', it is meant to represent all the basic steps that a computer takes to operate or accomplish any task. So, before discussing the basic functions of a computer, we must understand that what are the basic steps a computer follows when we work on it.

How does the computer work?

Both computer hardware and software work in parallel towards the proper functioning of the computer system. In particular, the working of any computer system mainly includes the following steps:

Accept data by users through input devices, such as mouse, keyboard, scanner, etc.

Accepted data is transferred to temporary memory and then sent for processing through a microprocessor (or CPU) as per given instructions.

Generate meaningful information or output from processed data and display it through output devices like monitors, printers, etc. 

Store the data permanently if desired by the user.

What are the basic functions of the computer?

Based on the fundamental working of a computer system, a computer mainly has four basic functions, namely:

Data Input
Data Processing
Information Output
Data and Information Storage

The above functions of the computer are also known as an input function, process function, output function, and storage function, respectively.

Functions of Computer

Data Input

As we know that computers cannot work on their own. According to this, data is required in the form of input by the users for the computer to perform certain tasks. Thus data input is considered to be the initial or first function of a computer system. The computer does nothing until data is inputted by the user (or a script or a program) to be processed as per given instructions.

Data can be supplied to the computer system manually, automatically, or both. Manual data is supplied using input devices whenever the computer requires it or whenever users want to accomplish certain tasks. In addition, automated data input can be done using automated scripts, applications, and robotics. It can intelligently feed predefined data into the computer or execute any task or program at a particular time, on start-up, based on user's action, click-activity, etc. 

Even with the data being automated, the instructions are configured indirectly by the users to some extent. Data can be supplied in computer word processing programs, spreadsheets, online forms, databases, etc. The data is given in raw form only.

The mouse and keyboard are one of the primary input devices of a computer system, which enables users to input data into the computer. However, there are many more input devices that help users to input data in various forms, such as text, numbers, images, audio, video, etc. For example, webcams can be used to input data in image or video form, a microphone can help input voice data, etc.

Mouse: A mouse is an input device that acts as a point-and-click device and helps to move the cursor and select specific objects on a computer's screen (also called a monitor). It can be connected to the computer both by wire and wirelessly.


Keyboard: The keyboard consists of several keys that help to input alphabet letters, numbers, signs, and other information. Like a mouse, it can also be wired and wireless.


Data Processing

Data processing is the main function of the computer system. CPU (Central Processing Unit) plays a major role in the data processing. Once the raw data is given to the computer, the processing part comes into play, according to which the supplied (or raw) data is manipulated according to instructions to turn it into meaningful information. 

There is always a constant development in technology to make modern computing devices better than their predecessors. There has also been a big improvement in the processing chip or CPU of the computer. Many modern computers nowadays use the CPU in conjunction with a graphics processing unit (GPU), making it an accelerated processing unit (APU). This combination of CPU and GPU integrates powerful graphics processing capabilities with the CPU's traditional arithmetic and local calculations, making computers faster, smoother, and more powerful.

The CPU of a computer is called the ‘brain’ of the computer because it controls all the functions. It processes user instructions, executes system scripts and commands to boot the OS (Operating System), runs programs, etc. It is also responsible for performing arithmetic and logical operations in computer systems. It can also store temporary data, instructions, and results with the help of a memory unit. Each instruction is sequentially processed by the CPU and goes through the following units: 

Control Unit: The Control Unit (CU) of the CPU controls all the activities and operations of the computer. It is also responsible for controlling input/output, memory, and other devices connected to the computer. In short, the control unit determines the sequence of operations and decodes the instructions into commands.

Arithmetic Logic Unit: The Arithmetic Logic Unit (ALU) of the CPU performs arithmetic and logical operations. The arithmetic unit performs mathematical operations such as addition, subtraction, division, and multiplication. The logical unit performs logical and decision operations such as AND, OR, equal, greater, and less than, etc. In addition, the logic unit is also responsible for performing many other operations such as comparison, selection, matching, data merging, and so on.

Memory Unit: The memory unit allows the CPU to temporarily store the data, program, intermediate and final results of the processed data. This is a temporary storage area but is vital to the functioning of the computer. All the inputs/outputs are first stored in the memory unit and then transferred to other units of the computer wherever necessary as per the instruction. It uses the primary memory (main memory) or RAM of the computer.

Functioning of CPU

Note: The Control Unit and the Arithmetic Logic Unit together make up a computer's CPU, which are hereby referred to as the primary components of the CPU.

Information Output

After the raw data supplied by the users is processed by the computer's processor, the processed data is sent from the primary memory to the output device by the CPU. This result is used for a meaningful purpose. The processed data or output is referred to as information. Information output or information retrieval is another basic function of a computer.

Output devices are typically used to present the final result of the processed data. Monitor and printer are the primary output devices of a computer system. By default, the monitor is the default output device for computers these days. However, there are a variety of other output devices and users can connect one or more output devices together. For example, speakers and headphones can be used for the retrieval of sound output.

The output received from the computer can also be stored in the form of soft copy or hard copy. Soft copy output refers to the information stored in the computer's storage mediums, while hard copy output is the information printed on paper, cloth, etc.

Monitor: A monitor, also called a visual display unit, is one of the primary output devices of a computer. It is made of glass, circuitry, adjustment buttons, power supply, etc., all enclosed within a casing. It is connected to a computer to digitally view the output contents (such as text, image, video, etc.) on the screen.


Printer: A printer is another output device that can be connected to a computer system to make a hard copy of the desired document, image, or information on paper. The printer takes electronic data from the computer and creates an exact copy of it in monochrome (in this context, black and white) or colors, depending on the type of printer. There are mainly two types of printers, impact, and non-impact printers.


Recommended: Types of Printers

Note: The process of transferring data between the computer system and its internal and external components is termed I/O (Input/Output) process and is done using I/O (Input/Output) devices.

Data and Information Storage

The fourth basic function of the computer system is data and information storage. A computer can store data temporarily, while information can be stored permanently, both internally and externally. Data is kept in memory until it is processed into a meaningful piece of information that can be permanently saved for future use or additional manipulation.

After the input (raw data) is given, it is first stored in the primary memory for temporary use. It is then sent for processing and the current or ongoing data is still saved on the primary memory. After the data is processed, the results of the processed data are again placed on the primary memory, which is then sent as a meaningful piece of information to the output units from the primary memory. The information is then stored in permanent storage. 

Multiple storage devices are used on the computer; however, RAM, ROM, and SSD/HDD play an important role in the functioning of the computer system. RAM is the primary memory and stores data temporarily, while ROM and HDD/SSD stores data permanently. Unlike HDD/SSD, data stored on ROM cannot be modified by users. Besides, users can take advantage of cloud storage to store their processed data permanently, which can be accessed from anywhere on various computing devices.

RAM: RAM or Random Access Memory is the main memory (or primary memory) of the computer and temporarily stores the current data (or ongoing data). It has fast read/write speeds and can be accessed quickly by the computer's processor (CPU). It is a volatile memory and the data stored in it is lost when the power supply is turned off.


ROM: ROM or Read-Only Memory is a non-volatile storage medium that permanently stores essential computer data such as firmware. As the name suggests, the data stored in ROM is read-only data and is not accessible to the user for modification. It is primarily read by the computer's processor to write/load boot-up data and system files into the primary memory.


SSD/HDD: SSD stands for Solid State Drive, while HDD stands for Hard Disk Drive. These are two different permanent storage devices used on a computer. Both can be connected internally and externally. Normally, a computer uses at least one of these storage devices internally to store the operating system. Unlike ROM, data in these storage devices can be erased and written by the users as per their wishes.



The functions of a computer typically include the following tasks: taking data, processing it, returning results, and storing it. To help computer systems perform these functions, computer devices can be classified as input devices, processing devices, output devices, and storage devices, respectively. Some specialized devices may participate in one or several functions.

For example, a hard disk drive can participate in the following two functions of a computer: input (when files are read from the HDD), and storage (when files are saved to the HDD). Similarly, the touch screen can take input as well as display output.

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