Classification of Computers
Generally, the word computer refers to a personal computer such as a desktop or laptop. However, we see different types of computers in our daily lives performing various tasks, for example while operating an ATM, purchasing groceries at the store, etc.
- 1 Purpose
- 2 Working principle
- 3 Classification of computers according to size and storage capacity
According to purpose, computers can be classified into two types:
General purpose computers
These computers are used for general use such as office applications, banking, invoice, sales analysis, and financial accounting. They are used at home, offices, and educational institutions.
Special purpose computers
These computers are designed to perform scientific applications, weather forecasting, space applications, etc.
According to the technology used, computers can be classified into three types — analog, digital, and hybrid computers.
These deal with analog data which represents the continuously varying physical quantities, such as current, voltage, or frequency. They are used to measure physical quantities like pressure, temperature, speed, etc., and to perform computation on these measurements. Examples are thermometer and speedometer.
These operate on digital data. Input and output is in the form of on/off type (digit 1 and 0). Digital computers are based on counting operation. Any data to be manipulated by a digital computer must be converted to a discrete (1,0) representation. The digital computers are mainly used in office, home, and industry.
These use the combination of digital and analog computers. These computers use digital-to-analog (DAC) and analog-to-digital (ADC) technology to deal with both types of data. They store and process both analog and digital data. Hybrid computers are mainly used in artificial intelligence. The ECG machine used in hospitals is an example of hybrid computer. ECG machine reads the heart beat as an analog signal and then converts it into digital signal to print the graph.
Classification of computers according to size and storage capacity
This is designed by interconnecting a number of processors. It has the highest processing speed with multiprocessing technology. It is mainly used in weather forecasting, biomedical research, aircraft design, remote sensing, and other areas of science and engineering. A supercomputer focuses on executing a few programs as fast as possible. Examples of supercomputers are CRAY YMP, CRAY2, NEC SX-3, CRAY XMP, and PARAM.
These are slower than the supercomputers in speed and processing power. They can support hundreds of users simultaneously. In one way, mainframes are more powerful than supercomputers because they support more programs simultaneously, while the supercomputer can execute a single program faster than a mainframe.
Mainframes have a very large storage capacity and can handle large database systems, such as patient information system in a big hospital or student information system in an university. Example of mainframes are DEC, ICL, and IBM 3000 series. The capacity of a mainframe can be a hundred or even a thousand times that of a modern PC.
This uses multiprocessing. It is capable of supporting hundreds of users simultaneously. It has a large storage capacity and operates at a higher speed. The minicomputer is used in multi-user system where various users can work at the same time. This type of computer is generally used for processing a large volume of data. It is also used as a server in Local Area Networks (LAN).
This has the lowest speed and storage capacity. Its CPU is a microprocessor. The 4 bit microprocessor chip was invented first. The 8 bit microprocessor chip was used in the first microcomputer. The microprocessor chip continues to improve 16 bit, 32 bit, and 64 bit chips.
Examples of microcomputer are IBM PC, PC-AT. The PC supports a number of input and output devices. Today’s microcomputer is so powerful that it can serve the purpose of a server, or sometimes that of a minicomputer that can be used as a server. The microcomputer can be categorized as below —
Desktop computers are also known as personal computer (PC). They are intended for use at a fixed location. They consist of CPU, monitor, speaker, keyboard, and mouse. Desktop computers are easy to upgrade and expand. They are also less expensive.
All in one computer
All in one computers are the new form of desktop PC. They have inbuilt CPU and monitor like that of a laptop. They can also have a touch screen monitor and are mounted on a desk like a standard monitor. CPU is mounted on the back side of the monitor. It has a USB port for connection of a mouse and keyboard.
A laptop has a built-in monitor, keyboard, touch-pad, and speakers to make a fully functional computer. The modern laptops also have touch screen, which minimizes the use of a keyboard or mouse. They are called laptops because of their small size and being light enough to be used while being placed on one’s lap.
A laptop can perform almost all jobs of a desktop. The main components of laptop are — touch pad, battery, AC adapter and ports. A user can work on a fully charged laptop without connecting it to a power supply for three to seven hours. A laptop has a power cable and AC adapter designed to be used with specific type of laptop. The laptop also have 3 – 4 USB ports to connect peripheral devices, a VGA or HDMI port to connect the projector and a slot to insert a memory card.
Many mobile devices work as specialised computers. These are normally used for internet, e-mail, photography, capturing and storing images and videos. These devices are portable and consume very less space. The various mobile computers are categorised as — tablets, smartphones, wearable devices, vehicle-mounted, handheld computers, e-book readers, etc. The most common are tablets and smartphones, which are discussed here.
They are handheld computers and are more portable than laptops. They use a touch sensitive screen for typing and navigation. The size of a tablet is about 7 to 10 inches. They work on specialized operating systems such as Android, Windows, and iOS. The iPad is an example of a tablet.
In addition to providing telephone services, a smartphone is designed to run a variety of applications (apps). They are small tablet computers and can be used for web browsing, watching videos, reading e-books, and playing games. Many apps can be installed on the smartphone which we use in our daily lives for booking tickets, bill payment, etc.
Personal Digital Assistants (PDAs)
They are just like a mobile phone with a touch screen and keypad. They have bigger screens than mobile phones. They use handwriting recognition software to enter text and are extremely portable and fit into pockets. They are a powerful computer that includes satellite navigation facilities (GPS), mobile phone capability, and versions of application software that have a limited range of functions.