Classification of Computers

The computers can be classified on the basis of two main criteria, which are on the basis of Technology used and their size and capacity.

On the Basis of Technology : 

According to the technology used, computers can be classified into three categories :

1. Analog Computers : Analog is a Greek word that denotes ‘similar’. An analog computer is a form of computer that uses continuous physical quantities like pressure, temperature, length, voltage etc. and convert them into numeric values. This type of computers are used in process control units. They are specifically used for scientific and engineering applications. They usually give approximate results because they deal with quantities that vary continuously.

2. Digital Computer : Those computers which operates on discrete values is known as digital computers. The discrete value are 0 & 1. They represent data, whether numbers, letters, or symbols, in binary form i.e. 0 and 1, and they work with numbers in the form of separate discrete digits. They are general purpose computers and can be used in different applications like commercial, administrative and mathematical. Since they can store different set of instructions and programs. There are three major elements in a digital computer which help in solving the problems they are: hardware, software and data. The data is processed by digital computers using arithmetic and logical operations and therefore, they are more reliable and fast. They are more accurate in comparison with analog computers. 
  • Special Purpose Computers
  • General Purpose Computers
Special Purpose Computers : Special purpose computers are designed to perform only specialized task for which they are meant. For example weather forecasting, medicine, space research, navigation of air flights etc. They may not have additional unnecessary options. They are designed with specific instructions to perform a particular type of work only.

General Purpose Computers : These General Purpose computers can be used for different kind of jobs, i.e., it can be programmed differently for different purposes according to users need. They are multi-purpose computers that cater the needs of different people. They are generally found in homes and offices. Their uses include preparation of documents, letters, reports, gaming, financial analysis, data recording and analysis etc.

3. Hybrid Computers : The Hybrid computers are the combination of analog and digital computers. They incorporate the technology of both of them, i.e. the digital component normally serves as the controller and provides logical operations, while the analog component normally serves as a solver of differential equations. These computers use analog to digital and digital to analog converters to convert the analog signals into discrete numbers and digital numbers to analog signals. Data is inputed with the help of analog devices and then it is converted to digital with the help of analog to digital converter.It is further processed by digital device and after processing it is again converted into analog signals within the help of digital to analog converter.

On the Basis of Size :

According to the basis of size, the computers can be classified as :

1. Super Computer : Supercomputer is the most powerful and fastest, and also very expensive. It is used to process large amount of data and to solve the complicated scientific problems. It can perform more than one trillions calculations per second. It has large number of  processors connected parallel. So parallel processing is done in this computer. In a single super computer thousands of users can be connected at the same time and the supercomputer handles the work of each user separately. Supercomputer are mainly used for:
  • Weather forecasting
  • Nuclear energy research
  • Aircraft design
  • Automotive design
  • Online banking
  • To Control Industrial units

2. Mainframe Computer : Mainframe computers are large and powerful machines. However, they fall short in terms of the computation ability seen in supercomputers. They are like big file servers, enabling multiple users from nearby and remote locations to access resources at the same time. Also known as big iron, these systems can handle massive amounts of data going in and out simultaneously.This makes them popular with businesses. They operate at a very high speed (more than micro and mini computers), have very large storage capacity and can handle the workload of many users. The processing speed of mainframe computers is measured in MIPS (Million Instructions Per Second) i.e. 200-1200 MIPS.

3. Mini Computers : Mini computers are much smaller in size than mainframe computers but are larger than microcomputers. They are also known as mid-range servers and were first developed as special purpose main frame computers. Their processing power is below that of mainframe systems but above the capabilities of personal computers. They are suitable for small business requirements of a server or host which supports hundreds of users at a time. Being multi-user they are used in interactive applications in industries, research organisations, colleges and universities.

4. Super Mini Computer : A superminicomputer, or supermini, is a minicomputer with high performance compared to ordinary minicomputers. The term was an invention used from the mid-1970s mainly to distinguish the emerging 32-bit minis from the classical 16-bit minicomputers. The term is now largely obsolete but still remains of interest for students/researchers of computer history.

5. Micro Computer : Micro-computers are small, low cost and single-user digital computers. A micro processor combined with memory and interface modules is called a micro-computer. The word 'micro' is used to represent the small physical size of the components used in design. The term micro computer is used to represent a small size computer system consisting of the three basic units CPU, memory and input-output interfaces. Micro-Computers are used extensively as "Personal Computers" and as "Home Computers". Personal Computers are built primarily for use of  professionals and by small companies.

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