Types of Computers based on Size and Working Principle
Types of Computers based on Working Principle
Based on the working principle, there are three categories of computers: Digital computers, Analog computers and Hybrid Computers
Digital Computer
The general-purpose computers that we use today are digital computers. They represent all information in the form of digitals. They are built to operate on numeric codes. They do any task by basic operations like counting, addition etc. The important advantage is that they are much faster and accurate.
Based on the purpose, digital computers are classified into two types: Special Purpose Computers and General Purpose Computers. Special purpose computer is a computer that is designed to perform a specific task. They permanently store the instructions. So they can work efficiently. Such computers find application in process control and instrumentation. Most of these computers have a lot of firmware and may use specialized processors.
Analog Computers
Analog computers operate by the principle of measuring continuous quantities like voltage, current, pressure, temperature etc. They are less accurate and flow. They are used in engineering and science applications. An electronic weighing scale is an example of an analog computer.
Hybrid Computers
Hybrid computers combine the features of digital and analog computers. Some calculations take place in analog and other calculations in digital principle. Bio-medical equipments make use of both analog and digital techniques. They accept input using analog mechanism, then convert data to digital form and process the data by means of permanent programs. They have dedicated processor chips and memory.
Types of Computers based on Size
General-purpose computers come in various sizes and capabilities (Computing power). Each type has it's own architecture and are used depending on the size of applications. For example small microcomputers are used by individuals; where as giant super computers are used by large organizations for extremely large scale applications. The terms that we use to describe the different types of computers are:-
➢ Microcomputers
➢ Workstations
➢ Minicomputers
➢ Mainframes
➢ Supercomputer
Microcomputers
Microcomputers are the small computers that are commonly found in offices, classrooms and homes. The term personal computer or PC is synonymous with microcomputer. However PC has a more specific meaning they reside on desktops.
A microcomputer is built around a microprocessor chip, which is the CPU. They are compact models with a monitor, CPU, memory and disk drives all in one unit (called system unit).
The IBM-PC compatibles and Apple macintosh are popular example of personal computer models.
Microcomputers are the most economical. Their uses are, for small business applications, as a home computer for entertainment, as a part of the 'home office'. They also find use in schools for educational purpose. Top business executives carry small laptop micros for record keeping and presentations. For serious professionals, they are also suitable for workgroup computing and collaborative work.
Workstations
Between minicomputers and microcomputers, in terms of processing power, is a class of computers known as workstations. Workstations differ significantly from microcomputer in the design of their CPU. They are based on a philosophy of CPU design called reduced instructions set computing (RISC), which results in faster processing of instructions. Companies like IBM, sun microsystems, DEC and Hewlett packard are the leading manufacturers of workstations.
Minicomputers
The power of minicomputers lies between microcomputers and mainframes. They are mainly used as multiuser systems. They have greater storage capacity and larger memories. They use specially designed CPUs. They are ideal for organizations and companies who need to maintain large volumes of data in databases. The major minicomputer manufactures are IBM, DEC, Data General etc.
Mainframe Computers
Mainframes are the largest type of computer in common use. They are designed to handle tremendous amounts of input, output and storage. Like minicomputers they also have large number of terminals through which multiple users can share their usage.
Mainframes are used in huge companies and government departments for running centralized applications. For example, data is a central database stored in the mainframe can provide shared access to all departments of various offices of an organization.
Inspite of their tremendous power, they are prohibitively expensive. Another drawback is that a breakdown of the mainframe would affect the entire organization.
Due to these disadvantages, the mainframe based computing has manufacturer of mainframes, IBM 4300 series, IBM sierra 3090, IBM ES 9000 series etc are examples.
Super Computers
A Supercomputer is the most powerful computer available. These machines are extremely fast and hence suitable for processing huge amounts of information. A super computer system uses a special architecture that enhance speed and capability of the machine. They make use of parallel processing with multiple CPUs or single CPUs having parallel architecture. Due to this they can perform billions of instructions in a second.
Scientists use super computers to build models of complex processes (simulation). One such process is nuclear fission. Here a super computer can simulate the actions and reactions of millions of atoms as they interact. Other applications are in weather forecasting, space exploration, geographical information systems etc.
The CRAY X-MP 416 CRAY I, NEC CX / 44, Blue Pacific of IBM and CRAY 2 were some of the early supercomputers. Indian Scientists have also done considerable research in the field of supercomputers. Scientists of C-DAC (Centre for Development of Advanced Computing - An Institution under Department of Electronics, Government of India) have succeeded in building a super computer named PARAM. Another Indian super computer is Anupam. At present it is used for weather predictions. Below are the lists of Super Computers used in India.
➢ Sahasrat (CRAY XC40) (1.46 petaflops)
➢ HPC (860 teraflops)
➢ Cray XC-30 (558.7 teraflops)
➢ PARAM YUVA II (524 teraflops)
➢ PARAM Ishan (121 teraflops)
➢ Virgo (97 teraflops)
➢ PARAM SHIVAY (38.1 teraflops)
➢ PARAM Kanchenjunga (15 teraflops)