Chapter 2 - Peripheral devices

megapixel

1 million pixels

digital camera

a device that captures still or moving images by recording them on a chip-based image sensor

photosites

a grid of tiny light-sensitive diodes

dot pitch (pixel pitch)

a measure of image clarity

Luminance

a measure of screen brightness usually expressed in candelas per square meter (cd/m2) with higher numbers indicating a brighter display

stylus

a pen shaped object with a tapered end that can be used for precise input and manipulation of small objects on screen

touch/trackpad

a touch-sensitive surface which you can tap and slide your fingers to manipulate the pointer, menus and other objects on the screen

integrated graphics

a type of graphics circuitry that's built into a computer's motherboard and uses system RAM for graphics processing

speech recognition

allows you to dictate commands and data using a microphone

pointing device

allows you to manipulate an on-screen pointer and other screen-based graphical controls

Esc (escape key)

an all purpose "go back" or undo key that hides menus and gets you out of various task modes

expansion bus

an electronic pathway that moves information between the microprocessor and RAM, and stretches to various ports and slots where data can be transferred to other electronic circuitry devices

CCD (charge coupled device)

an object onto a small image sensor that the lens in digital cameras focuses light from

peripheral device

any input, output, or storage equipment that might be added to a computer system to increase its functionality

keypad

arrow keys that move the screen-based insertion point

numeric keypad

calculator-styled keys

windows key

calls up the start screen used to select software applications and files

speech synthesizer

converts digital text into audio output

DLP (digital light processing)

creates an image by bouncing light off of microscopically small mirrors arranged on a semiconductor chip

duty cycle

determines how many pages a printer is able to churn out

keyboard

enters data and issues commands; the most important input device on desktop and laptops

graphics processing unit (GPU)

executes graphics commands, leaving the main processor free for other tasks

graphics tablet

features a pressure-sensitive surface and stylus for free-hand drawing

ink jet printer

has a nozzle-like print head that sprays ink onto paper to form characters and graphics

LCD (liquid crystal display)

produces on-screen images by manipulating light within a layer of liquid crystal cells

game controller

provides input to on-screen objects such as a pointer or character in a computer game

video memory

stores screen images as they are processed but before they are displayed

gestures

swipes, taps and other movements on a touchpad

duplex printing

the ability of a printer to print on both sides of the paper

response time

the length of time required for a pixel to change color to keep pace with the image being displayed on the screen

screen size

the measurement in inches from one corner of the screen diagonally across the opposite corner

color depth (bit depth)

the number of colors a device can display

screen resolution

the number of horizontal and vertical pixels that a device displays on a screen

aspect ratio

the relationship between the width and height of a displayed image

graphics card (graphics board/video card)

typically contains a graphics processing unit and special video memory

function keys

used for computer-specific tasks such as putting the computer into sleep mode, adjusting screen brightness, and using a second display screen

virtual keyboard

used to enter words and numbers on computers with touchscreens

mouse

used to move an on screen pointer, select various screen elements by clicking them, and move screen elements by dragging them

laser printer

uses the same technology as a photocopier to paint dots of light on a light sensitive drum

Ctrl (control key) and Atl (alternate key)

work in conjunction with other keys to invoke keyboard shortcuts