Interacting with the Computerlesson 2

essential concepts

This lesson includes the following sections: The Keyboard The Mouse and Its Variants Alternative Methods of Input Monitors Sound Systems Printers

A standard computer keyboard has about 100 keys

Most keyboards have keys arranged in five groups

1.Alphanumeric keys2.Numeric keypad3.Function keys4.Modifier keys5.Cursor-movement keys

The Keyboard

Invalid Password*****

Using a Mouse

Variations of the Mouse The Mouse and Its Variants

The Mouse and Its Variants - Variations of the MouseThe mouse is a pointing device. You use it to move a graphical pointer on the screen and to issue commands without using the keyboard. Using the mouse involves five techniques.Pointing: Move the mouse to move the on-screen pointer.

Clicking: Press and release the left mouse buttononce.

Double-clicking: Press and release the left mousebutton twice.

Dragging: Hold down the left mouse button as youmove the pointer.

Right-clicking: Press and release the right mouse button.

Variants of the Mouse - TrackballsA trackball is like a mouse turned upside-down. Use your thumb to move the exposed ball and your fingers to press the buttons.

A trackpad is a touch-sensitive pad that provides the same functionality as a mouse. To use a trackpad, you glide your finger across the surface.

An integrated pointing device is a small joystick built into the keyboard. To use an integrated pointing device, you move the joystick.

Many styles of trackballs are available

Devices for the Hand Optical Input Devices Audio-Visual (Multimedia) Input DevicesAlternative Methods of Input

With a pen-based system, you use an electronic pen to write directly on the screen and choose commands. Pens are common input devices for handheld computers, like PDAs.

Touch-screen systems accept input directly through the monitor by detecting the touch of a finger. Touch-screens are useful for selecting options from menus.

The two primary types of game controllers are joysticks and game pads. Game pads usually provide controls for each hand. Joysticks are popular for flight simulator and driving games..Alternative Methods of Input - Devices for the Hand

The user can point, tap, draw and write on the computers screen with a pen.

Alternative Input Devices - Optical Input DevicesBar code readers can read bar codespatterns of printed bars. The reader emits light, which reflects off the bar code and into a detector in the reader. The detector translates the code into numbers.

Image scanners digitize printed images for storage and manipulation in a computer. Optical character recognition (OCR) software translates scanned text into editable electronic documents.

Bar code readers commonly track sales in retail stores

Alternative Input Devices - Audio-Visual (Multimedia) Input Devices

Microphones can accept auditory input. A microphone requires a sound card in the PC, to digitize analog sound signals, and convert digital sound signals to analog form.

PC video cameras digitize full-motion images. Digital cameras capture still images. These cameras break images into pixels and store data about each pixel.

Monitors

Categories of Monitors

CRT Monitors

Flat-Panel Monitors

Comparing Monitors

Video Controllers

Monitors are categorized by the technology they use:Cathode ray tube (CRT) monitors

Flat-panel displaysMonitors - Categories of Monitors

Monitors - CRT MonitorsIn CRT monitors, electrons are fired at phosphor dots on the screen.The dots are grouped into pixels, which glow when struck by electrons.

Monitors - Flat-Panel Monitors

Most flat-panel monitors use liquid crystal display (LCD) technology.

Passive matrix LCD uses a transistor for each row and column of pixels.

Active matrix LCD uses a transistor for each pixel on the screen.

Thin-film transistor displays use multiple transistors for each pixel.

Monitors - Comparing Monitors When comparing monitors, consider four features:Size

Resolution

Refresh rate

Dot pitch

Monitors - Video ControllersThe video controller is an interface between the monitor and the CPU.

The video controller determines many aspects of a monitor's performance, such as resolution or the number of colors displayed.

The video controller contains its own on-board processor and memory, called video RAM (VRAM).

Sound Systems

Multimedia PCs come with a sound card, speakers, and a CD-ROM or DVD drive.

A sound card translates digital signals into analog ones that drive the speakers.

With the right software, you can use your PC to edit sounds and create special sound effects.

Printers

Categorizing Printers

Evaluating Printers

Dot Matrix Printers

Ink Jet Printers

Laser Printers

Printers - Categorizing Printers Printers fall into two categories:Impact printers use a device to strike an inked ribbon, pressing ink from the ribbon onto the paper.

Non-impact printers use different methods to place ink (or another substance) on the page.

Printers - Evaluating Printers When evaluating printers, consider four criteria:Image quality Measured in dots per inch (dpi). Most printers produce 300 600 dpi.Speed Measured in pages per minute (ppm) or characters per second (cps). Initial cost Consumer printers cost $250 or less, but professional printers can cost thousands of dollars.Cost of operation This refers to the cost of supplies used by the printer.

Printers -Dot Matrix PrintersDot matrix printers are a common type of impact printer.

A dot matrix printer's print head contains a cluster of pins. The printer can push the pins out to form patterns in rapid sequence.

The pins press an inked ribbon against the paper, creating an image.

Printers Ink Jet PrintersInk jet printers are an example of non-impact printers.

The printer sprays tiny droplets of ink onto the paper.

Ink jet printers are available for color and black-and-white printing.

Laser Printers How Do Laser Printers Work?Laser printers are non-impact printers.

They use heat and pressure to bond particles of toner to paper.

Laser printers are available for color and black-and-white printing.

lesson 2 review Essential conceptsIdentify the five key groups on a standard computer keyboard.

Identify the five essential techniques for using a mouse.

List three categories of alternative input devices.

Name two categories of computer monitor.

List the four criteria you should consider when evaluating monitors.

List the three most commonly used types of printers.