Computer Hardware
Computer Hardware
Computer hardware refers to the physical components of a computer that can be seen and touched by the user .By the use of these hardware devices, it made very easy for the computer for processing its data, store and retrieve. Hardware is one of the basic necessary part of a computer system.
Computer hardware also includes communication bus, input devices, output devices, etc.
Input Devices
An input device can defined as an electromechanical device that allows the user to feed data into the computer for analysis and storage and to give commands to the computer.the data is entered into the main memory thought the input devices. They accept instructions from the user and convert the accepted instructions into the machine language.
Some of the commonly used input devices are described below
Keyboard
It is one of the most common input devices. The user can type text and command using this device. The layout of the keyboard was borrowed from the regular typewriter with some additional keys. Keyboard is used to enter data or information in a computer system, which may be in numeric form or alphabetic form. When key is pressed, keyboard interacts with a keyboard controller and keyboard buffer.
Keyboard controller stores the code of pressed key in keyboard buffer. There are different types of keyboard such as QWERTY, DVORAK and AZERTY.
Pc from Google
It is a device that moves in all directions and control the movements of the cursor. Joysticks are used in flight simulators, CAD/CAM systems etc.
A joystick is similar to a mouse except that the movement of cursor on the screen stops working as soon as user stop moving the mouse. But with the joystick, the pointer continuously moving in the previously pointing direction.
It is a handheld electro- optical pointing device, which is used for making drawings, graphics and for menu selection. The pain contains a photocell in a small tube. It senses the light from the screen when it becomes closer and generates a pulse. It is used to especially in personal digital assistants (PDA). It is very useful in in identifying a specific location on the screen. However it does not provide any information when it held over a blank part of the screen.
Touch screen
It is an input device that accepts input when the user places of fingertip on the computer screen. Touch screens have an infrared beam that criss-cross the surface of a screen. The ability to interact directly with a display typically indicates the presence of a touch screen. Touchscreen is generally used in applications like ATM, hospitals, airline reservation supermarkets, etc.
Digitizers and Graphic Tablets
Graphic tablets have special commands to convert drawings, photos, etc to digital signal. It allows artists to create handmade images and graphical image with motion and action.
Keyboard controller stores the code of pressed key in keyboard buffer. There are different types of keyboard such as QWERTY, DVORAK and AZERTY.
Types of Keys on keyboard
The keys are categorised under the following groups
(a) Alphanumeric Keys include the alphabet keys (A, B, C,....,Z) and number keys(0, 1, 2,3,....9).
(b) Numeric keys are located at the right hand side of the keyboard. They consist of digits and mathematical operators.
(c) Function Keys are the programmable keys, i.e. the programs can assign some specific actions. They are numbered from F1 to F2.
(d) Cursor Control Keys include four directional (left, right, up, down) arrow keys that are arranged in a inverted T formation between the arrow keys there are four more keys to control the cursor. These are as follows
- Home It is used to return the cursor to the beginning of the line or the beginning of a document.
- End It moves the cursor to the end of line.
- Page Up When it is pressed, the page view will be moved up one page and cursor goes to the back page.
- Page Down When it is pressed, the page view will be moved down one page and cursor goes to the next page.
(e) Other Keys A keyboard contains some other keys such as follows
- Control Key It performs a Special operation with the combination of other keys.
- Enter Key it is used to finish and entry and begin the new entry in a document.
- Shift Key some keys on the keyboard like numeric key have a symbol printed on their upper portion shift key is used to print this symbols there are two shift keys on a Keyboard.
- Escape key (ESc) It allows a user to cancel or abort operations, which are executing at present. It opens start menu with the combination of control key.
- Delete Key it is used to to erase information from the computer's memory and characters on the screen.
- Caps lock key it is used to type the alphabet in capital letters it enables or disables all the letters from being typed in capital letters when this key is unable the alphabet would be in capital letters and when it is desired world the alphabet would be in small letters.
- Num lock key it is used to enable and disable the numeric keypad.
- Windows key it is used to open the start menu.
- Space bar key it provides a space between two words. It is the longest key on the keyboard.
Pointing Device
A pointing device used to communicate with the computer by pointing to the location on the monitor. Movements of the pointing device are echoed on the screen by moments of the pointer. Some commonly used pointing devices are mouse, trackball ,joystick, light pen, touch screen etc. Some of them are as follows
Mouse
It is a small handheld device having two buttons on its upper side and also have a small wheel between these buttons. It is a pointing device which provides a means to input data commands in graphic form by selecting thought moving and arrow called pointer on monitor. The mouse may be used to position the cursor on a screen,move an object by dragging or select an object by clicking.
There are three types of mouse as follows
- Wireless mouse
- Mechanical mouse
There are four actions of mouse as follows
- Click or Left Click It selects an item on the screen.
- Double click It is used to open a document or program
- Right click It displays the list of commands on the screen. Right clicking is used to access the properties of selected object.
Trackball
It is another pointing device which is an alternative to a mouse. Trackball is also used to control cursor moments and actions on a computer screen. It is generally built in laptop, since there is no space for the mouse to move on the laptop. Trackball is used on CAD/CAM workstations and sometimes seen on computerised special purpose workstation such as radar consoles in an air- traffic control room and Sonar equipment on a ship or submarine.
Joystick
It is a device that moves in all directions and control the movements of the cursor. Joysticks are used in flight simulators, CAD/CAM systems etc.
A joystick is similar to a mouse except that the movement of cursor on the screen stops working as soon as user stop moving the mouse. But with the joystick, the pointer continuously moving in the previously pointing direction.
Light pen
It is a handheld electro- optical pointing device, which is used for making drawings, graphics and for menu selection. The pain contains a photocell in a small tube. It senses the light from the screen when it becomes closer and generates a pulse. It is used to especially in personal digital assistants (PDA). It is very useful in in identifying a specific location on the screen. However it does not provide any information when it held over a blank part of the screen.
Touch screen
It is an input device that accepts input when the user places of fingertip on the computer screen. Touch screens have an infrared beam that criss-cross the surface of a screen. The ability to interact directly with a display typically indicates the presence of a touch screen. Touchscreen is generally used in applications like ATM, hospitals, airline reservation supermarkets, etc.
Digitizers and Graphic Tablets
Graphic tablets have special commands to convert drawings, photos, etc to digital signal. It allows artists to create handmade images and graphical image with motion and action.
Barcode Reader
It is an input device used for reading printed barcodes (universal product code) available on product to be sold. A barcode reader emits a beam of light which reflects off the barcode image. A light sensitive detector in the barcode reader identify the barcode image by recognising special bars at both the end of the image.
Once code is identified, it is converted into a numeric code. A perfect example of a barcode reader, use in a supermarket where barcode scanner do it's the price of a product. A barcode is a machine readable representation of information in the form of strips of dark and light ink.
Barcode
Optical Mark Reader (OMR)
OMR is the process of detecting the presence of intended market responses. OMR is mainly used to detect marks on a paper. It uses a beam of light that is reflected on the paper with marks to capture presence and absence of data marks. The OMR reader interprets the pattern of marks into a data record and send this to the computer for storage analysis and reporting. OMR is widely used to read the answer of objective type tests voting applications and other evaluation studies.
Optical Character Reader (OCR)
OCR is a technique for the scanning of a printed page, translating it and then using the OCR software to recognise the image as ASCII text that is editable. It translates the arrow of dots into text that the computer can interpret as Words and letters. OCR is widely used technique for acquiring the textual data from image . It is used in many applications such as telephone bills, electricity bills ,insurance premium etc.
Magnetic Ink Character Recognition (MICR)
MICR reads the characters by examining their shapes in a matrix form and their information is then passed on to the computer. The characters are printed using a special ink which contains iron particles that can be magnetised. It is generally used in banks to process the checks for recognising the magnetic encoding numbers printed at the bottom of a cheque.
Smart Card Reader
It is advice which is used to access the microprocessor of a smart card. There are two kinds of smart cards ;memory cards and microprocessor cards. . Memory cards are the cards which contain only non volatile memory storage components and some specific security login. Microprocessor cards contain volatile memory and microprocessor components the card is made up of plastic generally PVC. Smart cards are used in large companies and organisations for stronger security authentication.
It is advice which is used to access the microprocessor of a smart card. There are two kinds of smart cards ;memory cards and microprocessor cards. . Memory cards are the cards which contain only non volatile memory storage components and some specific security login. Microprocessor cards contain volatile memory and microprocessor components the card is made up of plastic generally PVC. Smart cards are used in large companies and organisations for stronger security authentication.
Scanner
It is used to convert the data and image on paper into the digital form. scanner is an optical input device and uses light as an input source to convert an image into an electronic form that can be stored on the computer. Scanner can be used for storing the documents in the original form that can be modified and manipulated later on.
The most common types of scanners are as follows
- Handheld Scanner
They are small which can be held in a hand. These are less expensive and less wide. Hence in order to scan a single page image multiple passes are required. But there handiness is a major advantage of handheld scanner.
2. Flatbed Scanner
They are large and more expensive scanners that create higher quality images. Flatbed scanner have a flat surface on which the printed image to be scanned, is placed. These scanners can scan a page in a single pass.
3. Drum scanner
They are medium size scanners with the rolling drum. The sheet is fed thought the scanners so that the drum rolls over the entire sheet to be scanned ( just as the sheets are fed in a fax machine).
2. Flatbed Scanner
They are large and more expensive scanners that create higher quality images. Flatbed scanner have a flat surface on which the printed image to be scanned, is placed. These scanners can scan a page in a single pass.
3. Drum scanner
They are medium size scanners with the rolling drum. The sheet is fed thought the scanners so that the drum rolls over the entire sheet to be scanned ( just as the sheets are fed in a fax machine).
Microphone (Mic)
We can send input to the Computer through a special manual input device called microphone or mic. A mic converts the received sound into computer's format, which is called Digitised Sound or Digital Audio.
Output device
An output device is any piece of computer hardware equipment used to communicate the result of data processing carried out by an information processing to the outside world. Output may be viewed on a computer monitor, heard thought speakers, printed on printers, etc.
The output produced by the output devices can be of the following forms
Monitor
It is also known as Visual Display Unit (VDU).
The monitor is provided alongwith the computer to view the display result. A monitor is of two kinds; mono-chrome display monitor and colour display monitor.
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