Four Basic Functions of Computer PDF

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Download the Four Basic Functions of Computer PDF for upcoming competitive exams. The Download link for the notes is given below at the end of this post.

▪ The capabilities of modern computers are vast and varied, allowing them to perform both simple and complex tasks with ease. With technological advancements, computer devices, and components are constantly evolving, making it difficult to categorize their functions.

▪ However, there are some fundamental functions that all computer systems perform regardless of their size, power, or modernity. In this article, we will discuss these basic functions, which encompass the core operations a computer undertakes to execute any task. Therefore, it is essential to understand the fundamental steps a computer follows before delving into its basic functions.

How does the computer work?

▪ The proper functioning of a computer system relies on both its hardware and software components working in tandem. The operation of any computer system typically involves the following steps:

Accepting Data

▪ The computer receives input data from the user via various input devices such as a mouse, keyboard, scanner, or microphone. The input data can take various forms such as text, images, videos, or sound.

Temporary Memory Transfer

▪ Once the data is received, it is temporarily stored in the computer’s memory for further processing. The data is organized into a format that the microprocessor or CPU can understand and act upon.


▪ The microprocessor or CPU executes a set of instructions that correspond to the processing of the data. These instructions can be predefined software programs or custom-made by the user. The processing can include mathematical calculations, logical comparisons, or data manipulations.

Output generation

▪ Once the data is processed, it is transformed into meaningful information that the user can interpret. The output is then displayed on output devices such as monitors, printers, or speakers. The output can take various forms such as text, images, graphs, or sound.

Permanent storage

▪ The user may choose to store the processed data permanently for future use. The data can be saved on internal or external storage devices such as hard drives, USB flash drives, or cloud storage. The stored data can be retrieved and used anytime, even after the computer system is turned off.

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What are the Four Basic Functions of the Computer?

▪ The four primary functions of a computer system are based on its fundamental operation, which includes:

  • Data input
  • Data processing
  • Information output
  • Data and information storage

▪ These functions are commonly referred to as input, process, output, and storage functions, respectively.

4 Basic Functions of the Computer
4 Basic Functions of the Computer
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Data Input

▪ Computers cannot operate independently and require input data from users to perform tasks, making data input the primary function of a computer system. Without input data, a computer remains idle.

▪ Data can be inputted into the system manually, automatically, or through a combination. Manual input is performed by users using input devices whenever required to accomplish specific tasks.

▪ Automated input can be done through scripted programs, applications, and robotics. It can intelligently feed predefined data into the computer or execute tasks and programs based on user actions, clicks, or set times.

▪ However, even with automated data, users configure the instructions to some extent. Data can be inputted into computer word processing programs, spreadsheets, online forms, databases, etc. Typically, input data is in its raw form.

▪ Although the mouse and keyboard are primary input devices, many other devices allow users to input data in various formats, including text, numbers, images, audio, video, and more. For example, webcams can input image or video data, while microphones can capture voice data.


▪ A mouse is an input device that lets users point and click, allowing them to move the cursor and select specific objects on a computer screen (or monitor). It can be connected to a computer via a wired or wireless connection.

Computer Mouse


▪ A keyboard is an input device with multiple keys that allow users to input letters, numbers, symbols, and other types of information. It is an essential tool for typing text and commands on a computer.

▪ Similar to a mouse, a keyboard can be connected to a computer via a wired or wireless connection. The keys on a keyboard can also be customized or programmed to perform specific functions or tasks. Additionally, several types of keyboards are available, including ergonomic keyboards, gaming keyboards, and virtual keyboards.

Computer Keyboard
Computer Keyboard (Image Credit: Pixabay)

Data Processing

▪ Data processing is one of the most essential functions of a computer system. The Central Processing Unit (CPU) is the main component responsible for data processing. Once raw data is provided to the computer, the processing function takes over, and the supplied data is manipulated based on instructions to generate meaningful information.

▪ Advancements in technology have led to the development of modern computing devices with improved capabilities. In particular, the CPU has undergone significant improvement over the years, and modern computers often use an Accelerated Processing Unit (APU) that combines both the CPU and Graphics Processing Unit (GPU). This integration of processing units provides a powerful combination of arithmetic, logical, and graphics processing capabilities, making modern computers faster, smoother, and more powerful.

▪ The CPU is often referred to as the “brain” of the computer as it controls all the computer functions. It processes user instructions, executes system scripts, boots the Operating System (OS), runs programs, and performs arithmetic and logical operations.

▪ The CPU can store temporary data, instructions, and results in a memory unit. The CPU sequentially processes each instruction and goes through the Control Unit (CU), Arithmetic Logic Unit (ALU), and Memory Unit.

Control Unit (CU)

The Control Unit (CU) of the CPU controls all the activities and operations of the computer, including input/output, memory, and other devices connected to the computer. It determines the sequence of operations and decodes instructions into commands.

Arithmetic Logic Unit (ALU)

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. 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 data, programs, and intermediate and final results of processed data. It is a temporary storage area but is vital to the functioning of the computer. All inputs/outputs are first stored in the memory unit and then transferred to other units of the computer as per the instruction. The computer’s primary memory (main memory) or RAM is used for this purpose.

Information Output

▪ Once the computer’s processor processes the raw data, the CPU sends the processed data from the primary memory to an output device for presentation as meaningful information. Information retrieval or output is another basic function of a computer system. The most common output devices are monitors and printers, with the monitor being the default output device for modern computers.

▪ However, users can connect multiple output devices together, such as speakers or headphones for audio output. The output can also be saved as either a soft or a hard copy. Soft copy refers to information stored in digital format on the computer’s storage media, while hard copy output is printed on physical media such as paper or cloth.


▪ A monitor, also known as a visual display unit, is a crucial output device of a computer system. It consists of various components, including glass, circuitry, adjustment buttons, and a power supply, all enclosed within a casing.

▪ The monitor is connected to a computer system to display the output contents, such as text, images, and videos, on the screen. It is an essential tool for viewing and interacting with digital information on a computer.

Desktop PC Monitor
Desktop PC Monitor


▪ Another vital output device is the printer, which can be connected to a computer system to create a hard copy of a document, image, or other information on paper. The printer receives electronic data from the computer and produces an exact replica in either monochrome (black and white) or colour, depending on the printer type.

▪ There are two primary types of printers: impact and non-impact printers. Impact printers use a mechanical mechanism to transfer ink or carbon onto paper, while non-impact printers use various technologies like inkjet, laser, or thermal to create the image or text.

Computer Printer
Computer Printer


▪ A plotter is an input device in computer-aided design (CAD) applications to create high-quality, large-scale graphics such as engineering drawings, blueprints, and maps.

▪ It works by drawing continuous lines with a pen or pencil, rather than by printing dots like a traditional printer. Plotters come in different sizes and can produce high-resolution, accurate output with precise line widths and colours.

▪ They are often used in architecture, engineering, and graphic design industries where large-scale, detailed prints are required. While plotters are not as commonly used today as they were in the past, they still play a critical role in certain industries where high-quality output is essential.

▪ Overall, monitors and printers play essential roles in outputting information from a computer system. While the monitor allows users to interact with digital information visually, the printer allows users to create hard copies of that information. These output devices make it possible for users to share information in a tangible form, whether for personal or professional use.

Data and Information Storage

▪ The fourth fundamental function of a computer system is data and information storage. A computer can temporarily store data in primary memory, while information can be stored permanently internally and externally. Data is held in memory until it is processed into meaningful information that can be permanently saved for future use or further manipulation.

▪ Once the input (raw data) is provided, it is temporarily stored in primary memory. The ongoing data is then sent for processing while still saved in primary memory. After the data is processed, the results of the processed data are again placed in primary memory. This meaningful information is then sent to the output units from primary memory and stored in permanent storage.

▪ Computers employ multiple storage devices, but RAM, ROM, and SSD/HDD are critical to their operation. RAM is the primary memory and stores data temporarily, while ROM and HDD/SSD store data permanently.

▪ Unlike HDD/SSD, data stored on ROM cannot be modified by users. In addition, users can use cloud storage to store their processed data permanently, which can be accessed from various computing devices regardless of location.

Random Access Memory (RAM)

▪ Random Access Memory (RAM) is a crucial component of the computer system, providing fast access to data and instructions that are currently being used by the computer’s processor.

▪ It is called “random access” because it allows the CPU to quickly read and write data to any location in memory, rather than having to search for it on a storage device like a hard drive.

▪ RAM is characterized by its speed and ability to store data temporarily, which makes it an essential part of the computer’s performance.

▪ RAM comes in various types, such as Dynamic RAM (DRAM) and Static RAM (SRAM), with DRAM being the most common type found in personal computers. It is designed to be volatile, meaning its contents are lost when the power supply is turned off.

▪ However, modern computers have advanced power management features that allow them to retain the data in RAM even when the system is turned off or in sleep mode. The amount of RAM a computer has can affect its performance, with more RAM allowing for faster processing and multitasking.

Read-Only Memory (ROM)

▪ ROM is a non-volatile storage medium that permanently stores essential computer data such as firmware. The data stored in ROM is read-only 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 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 they wish.

▪ Additionally, users can use cloud storage to store their processed data permanently, which can be accessed from anywhere on various computing devices.


The four basic functions of a computer system are input, processing, output, and storage. Input devices are used to take in raw data, processing devices manipulate the data to produce meaningful information, output devices display or transmit the results, and storage devices are used to store both temporary and permanent data and information. Different computer devices can participate in one or more of these functions, such as hard disk drives that can be used for input and storage and touch screens that can take input and display output.

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