Computer and its classification
 

[CENTER][FONT=Arial][B][U][SIZE=5]Computer[/SIZE][/U][/B][/FONT][/CENTER]

[FONT=Arial][B][U][SIZE=4]Definitions[/SIZE][/U][/B][/FONT]

[COLOR=black][FONT=Symbol][SIZE=3]·[/SIZE] [/FONT][/COLOR][COLOR=black][FONT=Arial][SIZE=3]A computer is, at its most basic, a machine which can take instructions, and perform computations based on those instructions.[/SIZE][/FONT][/COLOR]
[COLOR=black][FONT=Symbol][SIZE=3]·[/SIZE] [/FONT][/COLOR][COLOR=black][FONT=Arial][SIZE=3]A machine for performing calculations automatically.[/SIZE][/FONT][/COLOR]
[COLOR=black][FONT=Symbol][SIZE=3]·[/SIZE] [/FONT][/COLOR][COLOR=black][FONT=Arial][SIZE=3]Computer is an electronic device which has many units like [B]Input unit, Control unit and Output unit[/B]. Input unit consists of input devices like keyboard, mouse, scanner, light pen, etc., Output unit consists of output devices like printer, monitor, etc., Control unit controls all the actions of computer which consists of memory unit, Arithmetic and logic unit. [/SIZE][/FONT][/COLOR]


[COLOR=black][FONT=Arial][SIZE=3]A computer is one of the most brilliant inventions of mankind. Thanks to computer technology, we were able to achieve storage and processing of huge amounts of data; we could rest our brains by employing computer memory capacities for storage of information. Owing to computers, we have been able speed up daily work, carry out critical transactions and achieve accuracy and precision at work. Computers of the earlier times were of the size of a large room and were required to consume huge amounts of electric power. However, with the advancing technology, computers have shrunk to the size of a small watch. Depending on the processing power and size of computers, they have been classified under various types. Let us look at the classification of computers.[/SIZE][/FONT][/COLOR]

[B][U][COLOR=black][FONT=Arial][SIZE=4]Classification of Computers on the basis of operational principle[/SIZE][/FONT][/COLOR][/U][/B]

[FONT=Arial][COLOR=black][SIZE=3]Based on the operational principle of computers, they are categorized as analog, digital and hybrid computers.[/SIZE][/COLOR][/FONT]


[FONT=Arial][COLOR=black][SIZE=3][B]1. Analog Computers:[/B] These are almost extinct today. These are different from a digital computer because an analog computer can perform several mathematical operations simultaneously. It uses continuous variables for mathematical operations and utilizes mechanical or electrical energy.[/SIZE][/COLOR][/FONT]

[SIZE=3][FONT=Arial][COLOR=black][B]2. Digital Computers:[/B] They use digital circuits and are designed to operate on two states, namely bits 0 and 1. They are analogous to states ON and OFF. Data on these computers is represented as a series of 0s and 1s. Digital computers are suitable for complex computation and have higher processing speeds. They are programmable. Digital computers are either general purpose computers or special purpose ones. General purpose computers, as their name suggests, are designed for specific types of data processing while general purpose computers are meant for general use.[/COLOR][/FONT][/SIZE]


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[SIZE=3][FONT=Arial][COLOR=black][B]3. Hybrid Computers:[/B] These computers are a combination of both digital and analog computers. In this type of computers, the digital segments perform process control by conversion of analog signals to digital ones.[/COLOR][/FONT][/SIZE]


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[B][U][COLOR=black][FONT=Arial][SIZE=4]Classification on the basis of types[/SIZE][/FONT][/COLOR][/U][/B]




[FONT=Arial][COLOR=black][U][SIZE=4][B]1. Mainframe Computers:[/B] [/SIZE][/U][/COLOR][/FONT]

[FONT=Arial][COLOR=black][SIZE=3]Large organizations use mainframes for highly critical applications such as bulk data processing and ERP. Most of the mainframe computers have capacities to host multiple operating systems and operate as a number of virtual machines. They can substitute for several small servers.[/SIZE][/COLOR][/FONT]


[SIZE=3][FONT=Arial][COLOR=black][B][U][SIZE=4]2. Microcomputers:[/SIZE][/U][/B] [/COLOR][/FONT][/SIZE]

[SIZE=3][FONT=Arial][COLOR=black]A computer with a microprocessor and its central processing unit is known as a microcomputer. They do not occupy space as much as mainframes do. When supplemented with a keyboard and a mouse, microcomputers can be called personal computers. A monitor, a keyboard and other similar input-output devices, computer memory in the form of RAM and a power supply unit come packaged in a microcomputer. These computers can fit on desks or tables and prove to be the best choice for single-user tasks.[/COLOR][/FONT][/SIZE]

[FONT=Arial][SIZE=4][B][U]3. Personal Computers[/U][/B][/SIZE][/FONT]

[SIZE=3][COLOR=black][FONT=Arial]Personal computers come in different forms such as desktops, laptops and personal digital assistants. Let us look at each of these types of computers.[/FONT][/COLOR][/SIZE]



[FONT=Arial][COLOR=black][SIZE=3][B][U]Desktops:[/U][/B] [/SIZE][/COLOR][/FONT]

[FONT=Arial][COLOR=black][SIZE=3]A desktop is intended to be used on a single location. The spare parts of a desktop computer are readily available at relatively lower costs. Power consumption is not as critical as that in laptops. Desktops are widely popular for daily use in the workplace and households.[/SIZE][/COLOR][/FONT]

[SIZE=3][FONT=Arial][COLOR=black][B][U][SIZE=4]Laptops:[/SIZE][/U][/B] [/COLOR][/FONT][/SIZE]

[SIZE=3][FONT=Arial][COLOR=black]Similar in operation to desktops, laptop computers are miniaturized and optimized for mobile use. Laptops run on a single battery or an external adapter that charges the computer batteries. They are enabled with an inbuilt keyboard, touch pad acting as a mouse and a liquid crystal display. Their portability and capacity to operate on battery power have proven to be of great help to mobile users.[/COLOR][/FONT][/SIZE]

[SIZE=3][FONT=Arial][COLOR=black][U][SIZE=4][B]Notebooks[/B]:[/SIZE][/U] [/COLOR][/FONT][/SIZE]

[SIZE=3][FONT=Arial][COLOR=black]They fall in the category of laptops, but are inexpensive and relatively smaller in size. They had a smaller feature set and lesser capacities in comparison to regular laptops, at the time they came into the market. But with passing time, notebooks too began featuring almost everything that notebooks had. By the end of 2008, notebooks had begun to overtake notebooks in terms of market share and sales.[/COLOR][/FONT][/SIZE]

[SIZE=3][FONT=Arial][COLOR=black][B][U][SIZE=4]Personal Digital Assistants (PDAs):[/SIZE][/U][/B] [/COLOR][/FONT][/SIZE]

[SIZE=3][FONT=Arial][COLOR=black]It is a handheld computer and popularly known as a palmtop. It has a touch screen and a memory card for storage of data. PDAs can also be used as portable audio players, web browsers and smart phones. Most of them can access the Internet by means of Bluetooth or Wi-Fi communication.[/COLOR][/FONT][/SIZE]

[SIZE=3][FONT=Arial][COLOR=black][B][U][SIZE=4]Minicomputers:[/SIZE][/U][/B] [/COLOR][/FONT][/SIZE]

[SIZE=3][FONT=Arial][COLOR=black]In terms of size and processing capacity, minicomputers lie in between mainframes and microcomputers. Minicomputers are also called mid-range systems or workstations. The term began to be popularly used in the 1960s to refer to relatively smaller third generation computers. They took up the space that would be needed for a refrigerator or two and used transistor and core memory technologies. The 12-bit PDP-8 minicomputer of the Digital Equipment Corporation was the first successful minicomputer.[/COLOR][/FONT][/SIZE]

[SIZE=3][FONT=Arial][COLOR=black][U][SIZE=4][B]Servers[/B]:[/SIZE][/U] [/COLOR][/FONT][/SIZE]

[SIZE=3][FONT=Arial][COLOR=black]They are computers designed to provide services to client machines in a computer network. They have larger storage capacities and powerful processors. Running on them are programs that serve client requests and allocate resources like memory and time to client machines. Usually they are very large in size, as they have large processors and many hard drives. They are designed to be fail-safe and resistant to crash.[/COLOR][/FONT][/SIZE]

[SIZE=3][FONT=Arial][COLOR=black][B][U][SIZE=4]Supercomputers:[/SIZE][/U][/B] [/COLOR][/FONT][/SIZE]

[SIZE=3][FONT=Arial][COLOR=black]The highly calculation-intensive tasks can be effectively performed by means of supercomputers. Quantum physics, mechanics, weather forecasting, molecular theory are best studied by means of supercomputers. Their ability of parallel processing and their well-designed memory hierarchy give the supercomputers, large transaction processing powers.[/COLOR][/FONT][/SIZE]

[SIZE=3][FONT=Arial][COLOR=black][B][U][SIZE=4]Wearable Computers:[/SIZE][/U][/B] [/COLOR][/FONT][/SIZE]

[SIZE=3][FONT=Arial][COLOR=black]A record-setting step in the evolution of computers was the creation of wearable computers. These computers can be worn on the body and are often used in the study of behavior modeling and human health. Military and health professionals have incorporated wearable computers into their daily routine, as a part of such studies. When the users' hands and sensory organs are engaged in other activities, wearable computers are of great help in tracking human actions. Wearable computers do not have to be turned on and off and remain in operation without user intervention.[/COLOR][/FONT][/SIZE]

[SIZE=3][FONT=Arial][COLOR=black][U][SIZE=4][B]Tablet Computers[/B]:[/SIZE][/U] [/COLOR][/FONT][/SIZE]

[SIZE=3][FONT=Arial][COLOR=black]Tablets are mobile computers that are very handy to use. They use the touch screen technology. Tablets come with an onscreen keyboard or use a stylus or a digital pen. Apple's iPad redefined the class of tablet computers.[/COLOR][/FONT][/SIZE]