What is a Computer? – Definition, Parts, Types, Advantages and Limitations

In this article, we shall learn about the definition, parts, types, advantages, and limitations of a computer.

What is a Computer?

A computer is an electronic data processing machine that consists of such components that input the data, store, and process these data, and produce the results in the desired format.

Here, the term data represents the raw facts and figures. The data is entered into the computer system with the help of an input device like a keyboard, and the computer stores this data in its memory. After that, the computer processes these data according to the instructions provided by the user. Once the input data is processed, the computer displays the results with the help of output devices such as monitors, etc.

A computer can understand electric signals (binary signals) only. Where the electric signals are governed by turning ON and OFF the circuits of the computer system.

Sometimes, we refer to a computer as a computer system, it is because it consists of several components that are joined together to perform a task.

Parts of a Computer

A computer consists of several parts to perform different functions of the system. These parts are described as follows:

• Input Unit – The input unit is the collection of input devices such as a keyboard, mouse, scanner, touchpad, etc. The input device is the part of a computer system that accepts the data and instruction from the outside world, converts it into machine readable form, and then supplies it either to a memory device for storage or to the CPU for processing.
• Memory Unit – The memory unit, also called the storage unit, is the collection of memory devices of the computer. A memory device is a part of a computer system that is dedicated to storing the data, instructions, and information in the computer. Common examples of memory devices are hard disks, CDs, DVDs, pen drives, SD cards, etc.
• Processing Unit – The processing unit, also called the CPU (Central Processing Unit), is the main element of a computer system that converts the data into information. The process of conversion of data into information according to the user’s instruction is called processing. The CPU or processing unit is the part that is responsible for this purpose. Basically, the CPU of a computer system consists of two parts namely ALU (Arithmetic Logic Unit) and CU (Control Unit). The ALU is the part of the CPU where actual processing takes place, while the CU is the part that releases the control signals (called clock signals). The control signals to control the function of all the parts of the system and synchronize the various parts so that the computer can function efficiently.
• Output Unit – The output unit is the collection of output devices of the computer system. An output device is one that receives the processed data (called information) from the CPU and converts it into user-readable form and displays it on a screen or prints it on paper. Examples of output devices are a monitor, printer, plotter, projector, etc.

Types of Computers

With the change in technology, computers are also changed a lot. Thus, depending on the technology used (i.e. operating principle and data handling capability), the computers are classified into three major types as follows:

(1). Analog Computers

Analog computers work on the principle of measurements. In analog computers, the obtained measurements are converted into data. Therefore, these computers do not operate on direct numbers. Analog computers are less usual these days. Analog computers are primarily used for measuring voltage, current, temperature, speed, etc.

(2). Digital Computers

Digital computers work on the principle of the binary system (i.e. in the digital form of information). In the case of digital computers, the input signal is first converted into digital form and then stored or processed by the computer. These computers operate at high speed at more accuracy as compared to analog computers. Digital computers are used for general purposes and for processing of large data such as business finance data, school database reports, weather data, etc.

(3). Hybrid Computers

Hybrid computers are those that exhibit the features of both analog computers and digital computers. The hybrid computer uses sensors and other input devices to enter the data. Where sensors are generally those devices that can input analog signals. There are some mechanisms provided in these computers that convert the analog input into binary form so that the CPU of the computer can process them. The most popular examples of hybrid computers are smartphones, digital energy meters, tablets, laptops, modern desktop computers, etc.

Types of Digital Computers

Based on the size, storage capacity, and performance, digital computers are classified into four types namely Super Computers, Mainframe Computers, Mini Computers, and Micro Computers.

(1). Super Computers

Supercomputers are the most powerful computers in terms of data storage capacity, performance, and data processing. Supercomputers are special-purpose computers that are mainly used in research and scientific applications. For example, for launching and controlling a spacecraft by a space research agency like NASA, ISRO, etc. Supercomputers are the largest in size and are also quite expensive. The world’s first supercomputer is CDC 6600, invented in 1964.

Supercomputers are used in various large-scale applications such as communication, scientific research, engineering simulation, medical research, weather forecasting, weapon testing, getting knowledge about the effects of atomic weapons, etc. Some popular supercomputers are IBM’s Sequoia (America), Fujitsu’s K Computer (Japan), and PARAM Supercomputer (India).

(2). Mainframe Computers

Mainframe computers are also large-sized and expensive computers that are used in government departments and large businesses for handling large amounts of data and information. The mainframe computers are installed in a large room where air conditioning and other facilities are available. Just like supercomputers, mainframe computers are also able to process large amounts of data at high speed. The major areas where mainframe computers found applications are commercial banks, educational institutions, insurance companies, etc. Some popular mainframe computers are Fujitsu’s ICL VME and Hitachi’s Z800.

(3). Mini Computers

Mini computers are the types of digital computers that are not as powerful as supercomputers. However, they are still considered significantly powerful. The mini-computers are often used in small and medium-scale businesses and production houses. Like supercomputers and mainframe computers, mini-computers are also multi-user computers. Popular examples of mini computers are K-202, Texas Instrument TI-990, SDS-92, etc.

(4). Micro Computers

A microcomputer is a single-user general-purpose computer whose CPU is in the form of a VLSI (Very Large Scale Integration) chip. Microcomputers are the most widely used computer in the world because these are the cheapest among all the four types of computers. Microcomputers are used to perform general purposes tasks like communication, education, entertainment, etc. Popular examples of microcomputers are desktops, laptops, smartphones, tablets, PDAs, etc.

Advantages of Computers

There are several advantages of a computer. The chief advantages of a computer are as follows:

• High processing speed – A computer can process data at a very high speed. A computer takes only a few seconds for processing a large amount of data, which means it can process more than 1 lakh of instructions within a fraction of a second.
• High accuracy – A computer produces completely correct results, provided that the provided data and instructions to the computer are correct. Thus, a computer works on the concept of Garbage in Garbage out (GIGO).
• High storage capacity – A computer has very high storage capacity, which means it can store a huge amount of data in compact form for a very long period of time.
• Versatility – A single computer can be used to perform a variety of tasks like writing a letter, preparing a report, listening to music, hospital management, banking, etc.
• Diligence – Being a machine, a computer is free from tiredness, lack of concentration, monotony, etc. Thus, a computer processes the last instruction at the same speed at which it processes the first instruction.
• Reduction in paperwork and cost – As the computer makes the processes fast because by using a computer, we can perform a number of tasks by sitting in a place. Also, the information is conveyed digitally. Thus, the use of computer reduces the paperwork, speed up the process, and reduces the cost.

Limitations of Computers

Though, nowadays computers are extensively used in every field of life like education, business, banking, etc. However, there are some limitations of computers as follows:

• A computer has no IQ (Indigence Quotient). Therefore, it needs the user’s instruction to perform the tasks.
• A computer is a dumb machine, i.e. it cannot do anything itself.
• It cannot change the order of instructions on its own.
• The environment should be free from moisture and dust where the computer is to be used. Because these parameters affect the operation of a computer.
• A computer cannot take decisions based on the emotions like love, anger, etc.