CLASSIFICATION OF COMPUTERS Computers systems that is available in various sizes. Computers can be classified on the basis of purpose, size, generations and data processing techniques.
(1) Classification on basis of data processing techniques
We can classify them into three classes on basis of data processing technique:-
(a) Analog Computers
The analog computer is usually represented by a series of sine waves. These signals are varying frequency or amplitude. Analog technology is used by broadcasting and phone transmission conventionally. The analog computer recognizer data as a continuous measurement of a physical property such as length, weight, pressure, temperature, current etc. analog computer examples in clued an automobile speed meter and mechanical watch. Also flowing of current and voltage etc are common examples of analog computer. They are basically used in process industry and instruments that can directly.
(b) Digital Computers
Digital computers are high speed, programmable, electronic devices that perform mathematics calculations, compare values and store the results. They recognize data by counting discrete signals representing either a high (“on”) or low (“off”) voltage state of electricity. Numbers and special symbols can be reduced to representing by 1’s (“on”) and 0’s (“off”). In case digital technology the signals that travel can be represented in term of two states-positive (1) and non-positive (0). Each of these state digits is referred to as bit. The digital computers are used for measuring data in the digital form. The real life example of digital computer is a digital watch. Digital computer used for the purpose of business and education are also example of digital computers. Two types of digital computer:-
(a) Special purpose computers are those computers that are designed to meet the need of a special application. They are assigned to perform only a single job. So they execute their task quickly and efficiently. In these computer instruction are permanently. These computer used in missile technology, weapon designing, electronic application etc.
(b) General purpose computers are those which are designed a variety of jobs or applications. They are less efficient than special purpose computers. These computers used in banking, manufacturing, sales analysis, personal usage.
(3) Hybrid Computers
Those computers which employ both the features of analog and digital computer are known as Hybrid computer. The use of hybrid computer day to day as there are number of areas in the real world where need both analog and digital computers. Consider the example of an hospital: in a hospital there may be number of devices like E.C.G. machine etc. which are used to measure the person’s heart beat, temperature and other information. This is done by analog computers. The information is received from these devices is then supplied to digital computer to generate reports. STD/PCO is another example of hybrid computer.
Super computer are the most powerful and most expensive computers made. They are physically some of the large computers made. These have a very fast processing speed and can perform millions of processes in a second. Super computer consume enough electricity that could provide electricity to a number of houses. Super computers have a very fast memory which helps them to store and retrieve data very easily and quickly. Super computers are primarily used in weather forecasting, remote sensing, image processing, nuclear reactions, chemical reactions, study DNA structures by scientists and engineers. Super computer are often put in large rooms with special cooling systems, power protection and other security features. These computer are non portable. The first super computer developed in 1976 is the Cray-1 Super computer. India’s first super computer is PARAM and the latest one is PARAM 10000.
(2) Mainframe Computer
Mainframe computers are basically used in the large organizations like banks, flight scheduling, ticket reservations, and insurance companies. In a mainframe several computer terminals which basically contain keyboard and monitor are plugged into a single mainframe. These terminals act as a like input/output to a mainframe. A mainframe can house large amount of data which may contains millions of records. They are cheaper than Super computer but still are very costly. They occupy a lot of space and require air-conditioning and wiring to connect to each terminals. Mainframe is non portable computers. All the hardware device can be attached to the mainframe. To operate mainframe highly skilled staff is required. Some common mainframe series are MEHDA, DEC, ICL etc.
(3) Mini Computers
Mini computer is a small general purpose computer that is the next step down, being smaller and less expensive. They contain less memory and processing capabilities than a Mainframe. Like mainframes, they can handle much more input and output than personal computer can. They are commonly used as server in the network environment that can satisfy data sharing needs of other computers on the network. A large number of computers can be connected to a network with a minicomputer acting as a server. Some common Mini Computers are PDP-II and PDP-45.
Micro Computers or PC
Micro computer or Personal computer as they are so called, designed to meet the requirements of an individual. With the major changes in technology and cheaper hardware we could group the various hardware components like microprocessors, microchips and storage devices into a single machine called Micro Computers. As they were basically used for personal usage they came better to be known as Personal Computer. These are portable computers and can easily be transported. The Desktop computers, Tower case computer, Notebook computer and handheld computer all fall under this category. The famous Micro Computer is 32-bit microprocessor chips. Mostly used Micro Computer is PC-XT and PC-AT.
Laptop and Hand held Computers
Personal Computers which are very small in sizes and can easily carry out in our lap of hand are called Laptop Computer. They are portable computers and can be easily carried from one place to another. They are very light in weight and small in sizes. These computer do not require any external power source. These computer are costlier than PC. The storage capacity is also less in comparison to Personal Computer.