e s s e n t ia l c o n c e p t s le s s o n 2 Interacting with the Computer This lesson includes the following sections: • The Keyboard • The Mouse and Its Variants • Alternative Methods of Input • Monitors • Sound Systems • Printers The Keyboard A standard computer keyboard has about 100 keys Most keyboards have keys arranged in five groups 1. Alphanumeric keys 2. Numeric keypad 3. Function keys 4. Modifier keys 5. Cursor-movement keys ACADEMIC RECORDS Password * * * * * ENTER Invalid Password The Mouse and Its Variants • Using a Mouse • Variations of the Mouse The Mouse and Its Variants Variations of the Mouse The 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. 1. Pointing: Move the mouse to move the on-screen pointer. 2. Clicking: Press and release the left mouse button once. 3. Double-clicking: Press and release the left mouse button twice. 4. Dragging: Hold down the left mouse button as you move the pointer. 5. Right-clicking: Press and release the right mouse button. Variants of the Mouse Trackballs • A 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 Alternative Methods of Input • Devices for the Hand • Optical Input Devices • Audio-Visual (Multimedia) Input Devices Alternative Methods of Input Devices for the Hand • 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.. The user can point, tap, draw and write on the computer’s screen with a pen. Alternative Input Devices Optical Input Devices • Bar code readers can read bar codes—patterns 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 Categories of Monitors Monitors are categorized by the technology they use: • Cathode ray tube (CRT) monitors • Flat-panel displays Monitors CRT Monitors • In 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 Controllers • The 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 Printers • Dot 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 Printers • Ink 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-andwhite 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 blackand-white printing. le s s o n 2 r e v ie w E s s e n t ia l c o n c e p t s • Identify 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.
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