WHAT IS COMPUTER..?

WHAT IS COMPUTER..?

WHAT IS COMPUTER?

                    Computer is an advanced electronic device that takes raw data as input from the user and processes these data under the control of set of instructions (called program) and gives the result (output) and saves output for the future use. It can process both numerical and non-numerical (arithmetic and logical) calculations.

           Charles Babbage is called the "Grand Father" of the computer. The First mechanical computer designed by Charles Babbage was called Analytical Engine. It uses read-only memory in the form of punch cards.

DIGITAL COMPUTER

          The basic components of a modern digital computer are: Input Device, Output Devices , Central Processor Unit(CPU), mass storage device and memory. A Typical modern computer uses LSI Chips.  

Four Functions about computer are:

accepts data	Input
processes data	Processing
produces output	Output
stores results	Storage

Input (Data):

Input is the raw information entered into a computer from the input devices. It is the collection of letters, numbers, images etc.

Process:

Process is the operation of data as per given instruction. It is totally internal process of the computer system.

Output:

Output is the processed data given by computer after data processing. Output is also called as Result. We can save these results in thetorage devices for the future use.

Computer Classification( By Size and Power)

Computers differ based on their data processing abilities. They are classified according to purpose, data handling and functionality.

According to functionality, Computers are classified as:

• Analog Computer: A computer that represents numbers by some continuously variable physical quantity, whose variations mimic the properties of some system being modeled.

• Personal computer: A personal computer is a computer small and low cost. The term"personal computer" is used to describe desktop computers (desktops).

• Workstation: A terminal or desktop computer in a network. In this context, workstation is just a generic term for a user's machine (client machine) in contrast to a "server" or "mainframe."

• Minicomputer: A minicomputer isn't very mini. At least, not in the way most of us think of mini. You know how big your personal computer is and its related family.

• Mainframe: It refers to the kind of large computer that runs an entire corporation.

• Supercomputer: It is the biggest, fastest, and most expensive computers on earth.

• Microcomputer: Your personal computer is a microcomputer.

Hardware components:

• Mouse:

A computer mouse is a pointing device (hand control) that detects two dimensional motion relative to a surface. This motion is typically translated into the motion of a pointer on a display, which allows a smooth control of the graphical user interface.

Physically, a mouse consists of an object held in one's hand, with one or more buttons. Mice often also feature other elements, such as touch surfaces and "wheels", which enable additional control and dimensional input.

Advantages:

              1.Easy to use
              2.Not very expensive
              3.Moves the cursor faster than the arrow keys of keyboard.

• Keyboard:

 A computer keyboard is a typewriter-style device which uses an arrangement of buttons or keys to act as a mechanical level or electronic switch.A keyboard typically has characters engraved or printed on the keys (buttons) and each press of a key typically corresponds to a single written symbol. However, to produce some symbols requires pressing and holding several keys simultaneously or in sequence. While most keyboard keys produce letters, numbers or signs (characters), other keys or simultaneous key presses can produce actions or execute computer commands.

Keyboards are of two sizes 84 keys or 101/102 keys, but now keyboards with 104 keys or 108 keys are also available for Windows and Internet.

The keys on the keyboard are as follows:

Sr.No	Keys	Description
1	Typing Keys	These keys include the letter keys (A-Z) and digit keys (0-9) which generally give same layout as that of typewriters.
2	Numeric Keypad	It is used to enter numeric data or cursor movement. Generally, it consists of a set of 17 keys that are laid out in the same configuration used by most adding machines and calculators.
3	Function Keys	The twelve function keys are present on the keyboard which are arranged in a row at the top of the keyboard. Each function key has unique meaning and is used for some specific purpose.
4	Control keys	These keys provide cursor and screen control. It includes four directional arrow keys. Control keys also include Home, End, Insert, Delete, Page Up, Page Down, Control(Ctrl), Alternate(Alt), Escape(Esc).
5	Special Purpose Keys	Keyboard also contains some special purpose keys such as Enter, Shift, Caps Lock, Num Lock, Space bar, Tab, and Print Screen.

• Digitizing Tablet:

An input device that enables you to enter drawings and sketches into a computer. A digitizing tablet consists of an electronic tablet and a cursor or pen. A cursor (also called apuck) is similar to a mouse, except that it has a window with cross hairs for pinpoint placement, and it can have as many as 16 buttons. A pen (also called a stylus) looks like a simple ballpoint pen but uses an electronic head instead of ink. The tablet contains electronics that enable it to detect movement of the cursor or pen and translate the movements into digital signals that it sends to the computer.

For digitizing tablets, each point on the tablet represents a point on the display screen in a fixed manner. This differs from mice, in which all movement is relative to the current cursor position. The static nature of digitizing tablets makes them particularly effective for tracing drawings. Most modern digitizing tablets also support a mouse emulation mode , in which the pen or cursor acts like a mouse.

Digitizing tablets are also called digitizers, graphics tablets, touch tablets, or simply tablets.

• Track Ball

Track ball is an input device that is mostly used in notebook or laptop computer, instead of a mouse. This is a ball which is half inserted and by moving fingers on ball, pointer can be moved. Since the whole device is not moved, a track ball requires less space than a mouse. A track ball comes in various shapes like a ball, a button and a square.

• Joystick

Joystick is also a pointing device which is used to move cursor position on a monitor screen. It is a stick having a spherical ball at its both lower and upper ends. The lower spherical ball moves in a socket. The joystick can be moved in all four directions.The function of joystick is similar to that of a mouse. It is mainly used in Computer Aided Designing(CAD) and playing computer games.