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Learn about the keyboard, mouse, joystick, optical mark reader, OCR, touch-sensitive devices, and scanners for efficient data entry. Understand how these input devices work to interact with computers effectively.
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In put Devices and Media In order for a computer to do anything it must be told what to do.
The Keyboard • The keyboard is the most common input device available. Nearly every computer comes with one. It has a series of keys similar to a typewriter.
The Keyboard • Each key has a letter, number, symbol or word on it. • The user presses the key (or combination of keys) desired, causing a special code to be added to the keyboard buffer.
The Keyboard • This code (known as an ASCII code) remains in the buffer until the CPU is ready for it. • It is then decoded and the computer takes the appropriate action — displaying a character, moving the cursor, and so on.
The Keyboard • Keyboards are best suited for data entry or typing text documents, even though they can be used for several other things.
What Really is a Mouse • A mouse is a hand-held device that is moved on the surface of the desk or on a mouse-pad. • It has a ball underneath and usually two or more buttons (and maybe a wheel) on the top.
How it works • When the mouse is moved, this causes the ball to be moved. As the ball moves, the mouse pointer moves on the screen. • When the pointer is over an item that the user wishes to select, he/she can click one of the mouse buttons.
Mouse most commonly used for • selecting a menu • command or ‘pressing’ a button on the screen • highlighting icons and text • a pointing device.
Disadvantages of the mouse • It is limited to objects on the screen • When the ball gets dirty the mouse pointer moves erratically.
WHAT IS IT ? • A joystick is a device with a stick perpendicular to its base, as well as buttons on the stick and/or the base. • designed to resemble those used in fighter jets in order for it to feel more realistic
HOW DOES IT WORK • It is primarily used in playing computer games or in virtual reality • The user moves the stick, causing an object on the screen to be moved.
. When the user presses one of the buttons it usually triggers some appropriate action in the game or simulation, such as firing missiles.
Advantages • It gives the user the feeling of a more realistic action. • It moves objects in any direction.
Disadvantages • It is limited to certain applications. • A program must be specially written in order for a joystick to be used. • it does not suit most applications anyway
HOW DOES IT WORK? • An optical Mark Reader (OMR) is a device that senses thepresence of pencil and pen marks that are made on special forms.
WHAT DO THEY LOOK LIKE? • Such forms usually have several options with circles next to them. A person is asked to fill out the form by shading the circles for the correct options.
WHAT IS IT USED FOR? • This is an especially fast method of data entry for situations where a person is asked to choose various options such as questionnaires, multiple-choice exams or registration forms.
Advantages • Reduced cost of inputting large volumes of data • Fast method of inputting data • Less labour needed to input the data.
Disadvantages • If options are not shaded properly the machine may misread selections. • Forms that are creased jam the machine, causing down time. • Badly damaged forms have to be rewritten or keyed in manually.
The Optical Character Reader • A device that senses the presence of text by recognising the characters.
HOW DOES IT WORK? • When the document is scanned, a photo-electric device reads the characters, which are then converted to electrical signals. • The signals represent patterns that give an indication of the characters involved.
it is a fast method of data entry for documents that were already typed/written. • the accuracy of the input is dependent on the quality of the formation of characters.
What is it used for? • Capturing data from airline tickets • Reading postal codes • Capturing data from telephone and electricity bills
Advantages • Reduced cost of inputting large volumes of data • Quick method of inputting data • Less labour needed to input the data.
Disadvantages • The OCR may misread characters that are not formed properly.
Touch sensitive devices • A touch screen is another way to input data. • It is a specially mounted screen that is sensitive to touch, so you do not need to use a keyboard or mouse. • Banks, malls and restaurants use touch screens to provide information to the public.
Touch sensitive devices • A touch pad is a flat rectangular surface which also senses movement of a finger on its surface. • These devices are usually found on notebook computers. • A light pen is similar to a mouse, but you can move it over the screen and point at items on the screen to input data.
Scanner • A scanner allows you to transfer pictures, graphics and text to your computer. • It scans the image from the top to the bottom, one line at a time and transfers it to the computer. • You can then take that copy and use it in a paint program, send it out as a fax or print it.
Microphone • Data can be entered into a computer through a microphone. • The computer responds to this data by carrying out instructions, such as printing a document or turning the spoken words into text in a word processor. • These are called voice-activated or voice-input recognition systems.
Digitiser • Digitisers convert drawings and photographs into data for architects and makers of maps. • You can use a digital camera to store pictures, not on film but in an electronic format. • Pictures from the camera are then transferred to a computer using a cable and a computer program.
Digitiser • Moving pictures can also be captured by a computer using a video digitiser. • This method is often used by the television industry to edit TV programmes. • With digital video cameras now available in shops, video editing through computers will become commonplace.
