Учебное пособие состоит из двух частей и англо-русского словаря. Материалом для пособия послужило американское издание для изучающих компьютер P. Norton "Introduction to Computers"
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- Бұл бет үшін навигация:
- The Mouse
- Alternative Methods of Input
- Optical Input Devices
- Audiovisual Input Devices
UNIT 2. Input, Output, Storage Devices
Standard Methods of InputThe KeyboardA standard computer keyboard has about 100 keys; each key sends a different signal to the CPU. Most keyboards follow a similar layout, with their keys arranged in five groups. Those groups include the alphanumeric keys, numeric keypad, function keys, modifier keys, and cursor-movement keys. Most keyboards use the QWERTY layout, which gets its name from the first six keys in the top row of letters. Several ergonomically correct keyboards are available to help users prevent hand and wrist injuries. When you press a key, the keyboard controller notes that a key was pressed and places a code in the keyboard buffer to indicate which key was pressed. The keyboard sends the computer an interrupt request, which tells the CPU to accept the keystroke. The MouseThe mouse is a pointing device that lets you control the position of a graphical pointer on the screen without using the keyboard. Using the mouse involves five techniques: pointing, clicking, double-clicking, dragging, and right-clicking. Variants of the MouseA trackball is like a mouse turned upside-down. It provides the functionality of a mouse – but takes less space on the desktop. A trackpad is a touch-sensitive pad that may be built into the keyboard or added to the PC as a separate unit. It provides the same functionality as a mouse. To use a trackpad, you glide your finger across its surface. Many notebook computers provide a joystick-like pointing device built into the keyboard. You control the pointer by moving the joystick. On IBM systems, this device is called a TrackPoint. Generically, it is called an integrated pointing device. Brief History of the Mouse The mouse's history actually goes back to the early 1960s and a group of scientists and engineers at the Stanford Research Institute (SRI) in California. One of those scientists – Doug Engelbart – part of a team charged with developing ways to "augment human intellect." Specifically, Engelbart's group was looking for ways to use computer systems to help people solve complex problems. In his vision of this problem-solving system, Engelbart saw the need for a device that would enable the computer user to input data more efficiently than could be done using other standard input devices of the time, such as keyboards, light pens, and joysticks. With funding from NASA, Engelbart's team developed a series of simple tests to determine which input device enabled users to move a cursor around the screen in the least amount of time and with the least effort. In those tests, all the other devices were outdone by a simple wooden gadget – the mouse – that Engelbart had created with fellow scientist Bill English. The first mouse was a small wooden box. Rather than the hard rubber ball used in modern mice, Engelbart's mouse actually used two small wheels, placed perpendicular to one another on the mouse's underside. The user could move the mouse only up and down or side to side (moving diagonally was a problem), but the device worked well nonetheless and served as a prototype for the mouse we know today. The mouse was not noticed immediately by industry titans. In fact, few people, including leaders at SRI and Palo Alto Research Center (PARC), saw the mouse's value. Many did not see much of a future for computers in general, except for use by the military and some large businesses. This lack of vision, however, did not stop (or even slow) the visionary Engelbart. Throughout his career, he has described or developed technology that was considered to be ahead of its time. His discoveries and inventions in the fields of networking, hypertext, user interface technologies, and other computing disciplines continue to affect everyday computer users. Although the mouse did not make him rich, it helped launch one of the most brilliant and innovative careers in the history of computing science. Alternative Methods of InputDevices for the HandWith a pen-based system, you use a "pen" (also called a stylus) to write on a special pad or directly on the screen. Pen-based computers are handy for writing notes or selecting options from menus, but they are not well suited for inputting long text documents because handwriting-recognition technology has not yet achieved 100 percent reliability. Touch-screen systems accept input directly through the monitor. Touch-screen systems are useful for selecting options from menus, but they are not useful for inputting text or other types of data in large quantities. A game controller is a special input device that accepts the user's input for playing a game. The two primary types of game controllers are joysticks and game pads. Optical Input DevicesBar code readers, such as those used in grocery stores, can read bar codes, translate them into numbers, and input the numbers into a computer system. Image scanners convert printed images into digitized formats that can be stored and manipulated in computers. An image scanner equipped with OCR software can translate a page of text into a string of character codes in the computer's memory. Audiovisual Input DevicesMicrophones can accept auditory input. Using speech-recognition software, you can use your microphone as an input device for dictating text, navigating programs, and choosing commands. To use a microphone or other audio devices for input, your computer must have a sound card installed. A sound card takes analog sound signals and digitizes them. A sound card can also convert digital sound signals to analog form. PC video cameras and digital cameras can digitize full-motion and still images, which can be stored and edited on the PC or transmitted over a LAN or the Internet. жүктеу/скачать 0,7 Mb. Достарыңызбен бөлісу:
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