Computers of different kinds are available for our use today. Computers are classified according to the following factors:
- based on purpose
- based on operation or functionality
- based on size
Computer Classification Based on Purpose
- General purpose
- Special purpose
General Purpose Computer
A General purpose computer is designed in such way so that we can perform various common tasks.
- General purpose computer is one in which software applications can be installed and used.
- Capable of storing and executing applications
- Can be easily handled by anyone.
- Computers have the capability to do various functions and operations including writing and reading a document, editing with help of some software, maintaining database, doing mathematics calculation, security monitoring, and so on
ENIAC was the first general purpose computer in the year 1945. Today, we use personal computers, including laptop, desktop computer, smartphones, tablets and so on. All these devices are general purpose devices.
Special Purpose Computer
Special purpose computer is designed only for performing specific task and not for common use. These type of computers perform same operation again and again. Special purpose computer are very useful in traffic control system, video games, weather forecasting, mathematical calculator and so on. These computers don't need to store the program in memory because they are designed with built-in instructions so that it can do the particular operation efficiently and also gives fast processing speed. The main drawback of this computer is that they lack versatility. The ABC (Atanasoff-Berry computer) computer was the first special purpose computer built during the year 1939-42.
Computer classification based on operation or functionality
Usually, computers accept data, perform some operation on that data and finally returns results to the user. Based on the operation and functionality, the computers are classified into following types.
- Analog Computer
- Digital Computer
- Hybrid Computer
Analog computer is one of the earliest computers which process only the analog signals/analog data.
- Analog data is nothing but a continuous form of physical signals that continuously vary in nature.
- Example of physical quantities are pressure, voltage, current, temperature and so on.
- These analog values are always measured with respect to time.
Handing of analog computers are very complex for a common man's needs. Hence, it has been replaced by Digital computer for general use. However, it is being used in some scientific and industrial applications for measuring pressure, voltage, frequency, current and so on.
Example of some applications are:
- flight aircraft simulators
- control systems
Computers are in use for some specific applications, some examples of these computers are:
- Slide rule
- Operational amplifiers
- Differential analyzers
- Electronic Analog Computers
Digital computer is a computer that process the digital data (sometimes, we can say digital signal) as binary digits like 0 and 1.
- Digital computer performs numerical calculations.
- Digital computer uses the discrete values that gives standard and accurate results and does not vary continuously.
- Digital computers are general purpose computers.
- A Digital computer consist of 4 major components - input devices, output devices, central processing unit and memory.
- Example of these computers: desktop, laptop, smartphones.
Hybrid computer is a computer that can process both analog and digital data. It can use both continuous analog signal and discrete values for solving a problem. Most of the computers in today's world are the hybrid computer. They can accept analog signal and converts them into digital form before processing. These computers provide very high speed performance. For example, they are used in different applications like hospitals, airlines, industries, scientific, real-time applications and so on.
Examples: Electrocardiogram used in:
- ATM machines
- Computing embedded in Petrol bunks
- Ultrasound scans
- Fingerprint scanners with digital features
Computer classification based on Size
- Mainframe computer
- Mini computers
- Micro computer
Supercomputer is a very powerful, high performance and super fast computer designed for a specific task.
- Supercomputer is an architectural and operational model based on grid and parallel processing.
- Supercomputer is embedded with thousand of processors that able to execute billions or trillions of instructions per second.
- This type of computer is mainly used for a large organization that requires high computing power.
- The supercomputer's performance is measured in the form of FLOPS (Floating- point operations per second).
There are many applications where the supercomputer is used such as:
- weather forecasting
- scientific research areas
- data mining
- military and defence
- airline industry
These computers are very expensive compared to others. The first supercomputer was developed in 1960 by Seymour Cray in a Control Data Corporation(CDC).
A mainframe computer is a very large, faster, and more expensive computer that has huge storage space so that it can handle the massive amount of data. It is also known as big iron. Its performance is measured in MIPS (millions of instructions per second). It is mainly used for large organizations, research, bank transactions, census data processing, maintaining patient records in large hospitals, online transaction, airline tickets reservation, etc. It can enable multiple users to access the machine at the same time. Mainframe computers are often used as servers. Some manufacturers of mainframe computers are IBM, Hitachi, Bull, DEC, Fujitsu, etc. The UNIVAC I (UNIVersal Automatic Computer I) was the first mainframe computer developed in 1951 by J. Presper Eckert and John Mauchly .
Minicomputer is a smaller computer, its size lies between the mainframes and microcomputers, which was developed in the mid-1960s. Minicomputers support multi-processing which means that multiple users can access the system at the same time. Minicomputers are also called midrange computers. The PDP-8 (programmed Data Processor) was the first 12-bits minicomputer which was developed by Digital Equipment Corporation in 1965. The minicomputer is mainly used to handle complex tasks, and provide a better user interface. Minicomputer is used for manufacturing control, data management, scientific and engineering computation, small or mid-range business environment, business transaction processing, file handling, database management, and scientific applications.
Microcomputer is a very small computer compared to minicomputer and others. It uses the microprocessor as a CPU (Central Processing Units). Microcomputer is the smallest memory, highly portable, and less power consumption. These computers are generally referred to as personal computers (PCs) that are used in our day-to-day life applications. This computer is often used at home and in the office. It can process the request from one person at a time. Examples of these computers are Desktop, Laptop, and handheld devices. The Micral was the first microcomputer in 1973 by the French company Réalisation d'Études Électroniques (R2E).