Input Devices

Chapter 2: Input Devices

Input is any data or instruction entered into the computer's memory while input device enables user to direct the computer activities.

Input devices are the peripherals used to provide data and control signals to an information processing system i.e. the computer.

KEYBOARDS

Type writer-style keyboard which uses an arrangement of keys, to act as a mechanical levers or electronic switches. It allows the computer to enter words, numbers, punctuation, symbols and specials function commands into the computer's memory.

How the keyboards work? When we press a key, the keyboard sends a digital impulse through a cable to the computer. When the computer receives the impulse, it displays a character, i.e. a letter, number, punctuation mark, even a symbol on the display monitor.

The character appears at the on-screen location of the cursor, which shows where text will appear when we type. The cursor may be a blinking vertical line, a blinking underscore, or highlighted box.

Type of keyboards:

• Enhanced or Extended (Macintosh equivalent) keyboard is the typically 101 keys laid out in the QWERTY fashion, connected to the computer by a cable.
• Cordless keyboard uses infrared or radio wave signals.
• Ergonomic keyboard is designed to help cumulative trauma disorder (CTD) or damage to nerve tissue in the wrist and hand due to repeated motion (for those who're using keyboards for more than 12 hours a day, this type of keyboard is highly recommended).

Special keys on the keyboard. We can use the mouse or cursor-movement keys (also called arrow keys) to move the cursor around whenever we don't want to type where the cursor is located.

A Toggle key is a key named after a type of electrical switch that has only 2 positions: ON and OFF. Example are the Caps Lock, Num Lock keys.

Functions keys are the ones above the letters and numbers that are labeled F1 through F10, F12 or F15, which are used to provide different commands, depending on the program in use.

Near the function keys, is the Esc key, short for escape. Its function also depends on which program you're using, but it's generally used to interrupt or cancel an operation.

Modifier keys (known because they'll modify the meaning of the next key we press) are those keys have no effect unless we hold them down and press a second key. We use these keys for keyboard shortcuts, which provide quick keyboard access to menu commands.

MOUSE

Mouse is a pointing device that functions by detecting 2D motion relative to its supporting surface. To put it more simply, it gives the user a control on the movement of the on-screen pointer.

Magic Mouse by Apple, Inc. (I don't own this picture.)

Pointer is the on-screen symbol that signifies the type of command, input, or response user can give. Actions using mouse are like click (one-finger tap), double-click, twice-click, right click (2 fingers-tap), selecting, dragging, zooming (with Control Key being hold down - for Mac user) and etc.

Types of mice:

• "Magic" mouse is developed by Apple, Inc. with seamless Multi-touch surface and laser-tracking engine. As it uses Bluetooth wireless technology, no worries of annoying cables around your keyboard.
• Cordless mouse uses infrared signals to connect to the computer's IrDA port; it must be within sight of the receiving port.
• Wheel mouse contains a rotating wheel used to scroll vertically within a text document, connects to PS/2 Port or USB port.

Other types of pointing devices:

• Touch screen - pressure-sensitive panel that detects where we tapped the display screen with fingertip(s).
• "Magic" Track Pad - developed by Apple, Inc. uses the same Multi-touch tech on the notebooks. It connects to iMac or MacBook via wireless Bluetooth connection.
• Trackball - consists of a ball held by a socket containing sensors to detect a rotation of the ball about 2-axes.
• Pointing sticks - Small, stubby nub that protrudes from the computer's keyboard. It's pressure sensitive.
• Joystick - a device with large vertical lever that can be moved in any direction. Often used to control the motion of an on-screen object in a computer game or training simulator.
• Light pens - Contains a light source that triggers the touch screen's detection mechanism. Used for detailed works by designer.
• Stylus - it has the tip that is dry and semi-blunt and are commonly used for PDAs.

MICROPHONE

As for the audio input we can use the microphone. Microphone is a device that converts sound input into electrical signals that computer can process.

Speech recognition is a type of input in which the computer recognizes words spoken into a microphone. Special software and a microphone are required. Early tech used discreet speech recognition while latest tech uses continuous speech recognition, where the user doesn't have to pause between words.

As for the video input, we can use webcam. Webcam is a video camera which feeds its images in real time to a computer or computer network, often via USB, ethernet even WiFi.

Alternative input devices are scanners and fax machines.

Scanner is a device that can be used by using optical character recognition (OCR) software. Its automatically converts the scanned text into a text file.

Flatbed-scanner is a scanner that can work only s single sheet of paper at one time.

Sheet-fed scanner is a type of scanner that draws in the sheets to be copied by a roller mechanism.

A Barcode is an optical machine-readable representation of data, which shows data about the object to which it attaches. While a barcode reader is a hand-held or desktop-mounted scanning device that reads an item's Universal Product Code (UPC), which is a pattern of bars printed on merchandise that the store's computer system uses to retrieve information about an item and its price.

Magnetic-Ink Character Recognition (MICR) is a system that encodes the bank, branch, account number on each cheque. After a customer used a cheque, the bank has to enter manually only the amount of the cheque.

Optical Mark Reader (OMR) is a scanning device that sense the magnetized marks from 2B pencil on OMR answer sheet to determine which response marked.

Alright, I think that's all that have been covered in class today. Well, there are few things I added as in the examples I used in here just to add the some extra flavours. Anyway, I'll post the lab practices which was on Windows Explorer later.