Texts for tests Hardware. Input/Output hardware icon

Texts for tests Hardware. Input/Output hardware

Скачати 26.44 Kb.
НазваTexts for tests Hardware. Input/Output hardware
Розмір26.44 Kb.

Texts for tests

  1. Hardware. Input/Output hardware.

Text II. Hardware

The basic operations of computing consist of (1) input, (2) processing, (3) output, and (4) storage. Communications (5) adds an extension capability to each phase.

Hardware devices are categorized according to which of these five opera­tions they perform. (1) Input hardware includes the keyboard, mouse, and scanner. (2) Processing and memory hardware consists of the CPU (the processor) and main memory. (3) Output hardware includes the display screen, printer, and sound devices. (4) Secondary storage hardware stores data on diskette, hard disk, magnetic tape devices, and optical-disk. (5) Communi­cations hardware includes modems.

As we said earlier, a system is a group of related components and operations that interact to perform a task. Once you know how the pieces of the sys­tem fit together, you can then make better judgments about any one of them. And you can make knowledgeable decisions about buying and operating a computer system.

^ Hardware Categories

Hardware is what most people think of when they picture computers. Hard­ware consists of all the machinery and equipment in a computer system. The hardware includes, among other devices, the keyboard, the screen, the printer, and the computer or processing device itself.

As computing and telecommunications have drawn together, people have begun to refer loosely to any machinery or equipment having to do with either one as "hardware." This is the case whether the equipment is a "smart box," such as a cable-TV set-top controller, or (sometimes) the connecting cables, transmitters, or other communications devices.

In general, computer hardware is categorized according to which of the five computer operations it performs:

• Input • Secondary storage

• Processing and memory • Communications

• Output

External devices that are connected to the main computer cabinet are referred to as "peripheral devices." A peripheral device is any piece of hard­ware that is connected to a computer. Examples are the keyboard, mouse, monitor, and printer.

^ Input Hardware

Input hardware consists of devices that allow people to put data into the computer in a form that the computer can use. For example, input may be by means of a keyboard, mouse, or scanner. The keyboard is the most obvious. The mouse is a pointing device attached to many microcomputers. An example of a scanner is the grocery-store bar-code scanner.

• A keyboard includes the standard typewriter keys plus a number of specialized keys. The standard keys are used mostly to enter words and numbers. Examples of specialized keys are the function keys, labeled Fl, F2, and so on. These special keys are used to enter commands.

• A mouse is a device that can be rolled about on a desktop to direct a pointer on the computer's display screen. The pointer is a sym­bol, usually an arrow, on the computer screen that is used to select items from lists (menus) or to position the cursor. The cursor is the symbol on the screen that shows where data may be entered next, such as text in a word processing program.

• Scanners translate images of text, drawings, and photos into digital form. The images can then be processed by a computer, dis­played on a monitor, stored on a storage device, or communicated to another computer.

^ Text III. Output Hardware

Output hardware consists of devices that translate information processed by the computer into a form that humans can understand. We are now so exposed to products output by some sort of computer that we don't consider them unusual. Examples are grocery receipts, bank statements, and grade reports. More recent forms are digital recordings and even digital radio.

As a personal computer user, you will be dealing with three principal types of output hardware—screens, printers, and sound output devices.

screen: The screen is the display area of a computer. A desktop computer or video terminal (such as those listing flight information in airports) will use a monitor, a high-resolution screen. The monitor is often called a CRT, for Cathode-Ray Tube, the familiar TV-style picture tube.

printer: A printer is a device that converts computer output into printed images. Printers are of many types, some noisy, some quiet, some able to print carbon copies, some not.

sound : Many computers emit chirps and beeps. Some go beyond those noises and contain sound processors and speakers that can play digital music or human-like speech. High-fidelity stereo sound is becoming more important as computer and communications tech­nologies continue to merge.

  1. ^ Communications and Connectivity.

Text VII. Communications & Connectivity

Communications, also called telecommunications, is the electronic transfer of information from one location to another. It also refers to the electromagnetic devices and systems for communicating. The data being communicated may consist of voice, sound, text, video, graph­ics, or all of these together. The instruments sending the data may be tele­graph, telephone, cable, microwave, radio, television, or computer. The distance may be as close as the next room or as far away as the outer edge of the solar system.

The television set is an instrument of communications, but it is a low-skill tool. That is, the many people of a mass audience receive one-way communications from a

few communicators. This is why television (like AM/FM radio, newspapers, and music CDs) is called one of the mass media. Telephone systems are not mass media, since they involve two-way com­munications of many to many. But they, too, are low-skill communications tools. By contrast, linkages of microcomputers have allowed some people with a fairly high level of skill to achieve two-way communication with other people. The ability to connect devices by communications technology to other devices and sources of information is known as connectivity.

3. E-mail.


"E-mail is so clearly superior to paper mail for so many purposes," writes New York Times computer writer Peter Lewis, "that most people who try it cannot imagine going back to working without it." Says another writer, e-mail "occupies a psychological space all its own: It's almost as immediate as a phone call, but if you need to, you can think about what you're going to say for days and reply when it's convenient."

E-mail, or electronic mail, links computers by wired or wireless connec­tions and allows users, through their keyboards, to post messages and to read responses on their display screens. With e-mail, you dial the e-mail system's telephone number, type in the recipient's "mailbox" address, and then type in the message and click on the "Send" button. The message will be sent to the recipient's mailbox. To gain access to your mailbox, you dial the e-mail system's telephone number and type in the address of your mailbox and your password, a secret word or numbers that limit access. You may then read the list of senders and topics, read the messages, print them out, delete them, or download (transfer) to your hard disk.

If you're part of a company, university, or other large organization, you may get e-mail for free. Otherwise you can sign up with a commercial online service (America Online, CompuServe, Prodigy), e-mail service (such as MCI Mail), or Internet access provider (such as Netcom's NetCruiser or PSI's Pipeline USA).

E-mail has both advantages and disadvantages:

^ Advantages of e-mail: Like voice mail, it helps people avoid playing phone tag or coping with paper and stamps. A message can be as simple as a birthday greeting or as complex and lengthy as a report with sup­porting documents. By reading the list of senders and topics displayed on the screen, you can quickly decide which messages are important. Send­ing an e-mail message usually costs as little as a local phone call or less, but it can go across several time zones and be read at any time.

^ Disadvantages of e-mail: Nevertheless there are some problems: You might have to sort through scores or even hundreds of messages a day, a form of junk mail brought about by the ease with which anyone can send duplicate copies of a message to many people. Your messages are far from private and may be read by e-mail system operators and others; thus, experts recommend you think of e-mail as a postcard rather than a private letter. Mail that travels via the Internet often takes a circuitous route, bouncing around various computers in the country, until one of them rec­ognizes the address and delivers the message. Thus, although a lot of mes­sages may go through in a minute's time, others may be hung up because of system overload, taking hours and even days.

Nevertheless, the e-mail boom is only just beginning. In fact, it is perhaps the principal reason for the popularity of the Internet, as we shall discuss. The U.S. Postal Service is planning to offer e-mail with features of first-class mail, including "postmarks" and return receipts.

What, however, if you want to meet face-to-face with someone who is far away? Then you can use videoconferencing or picture phones.

^ 4. The Internet.

Text I. The Internet: What It Is, Where It Came From

Called "the mother of all networks," the Internet, or simply "the Net," is an international network connecting approximately 36,000 smaller networks.

To connect with it, you need pretty much the same things you need to connect with online services and BBSs: a computer, modem, tele­phone line, and appropriate communications software.

Whereas the number of users of commercial services doubled in 1995, to about 12.5 million, during the same year the number of active users of the World Wide Web jumped from 1 million to 8 million. According to Nielsen Media Research—the company that does the famous Nielsen TV ratings— approximately 37 million people, or 17% of the U.S. and Canadian popula­tion 16 and older, have access to the Internet. Some 24 million of them used it during the latter half of 1995, spending an average of 5 hours and 28 min­utes on it per week.

Created by the U.S. Department of Defense in 1969 (under the name ARPAnet—ARPA was the department's Advanced Research Project Agency), the Internet was built to serve two purposes. The first was to share research among military, industry, and university sources. The second was to provide a system for sustaining communication among military units in the event of nuclear attack. Thus, the system was designed to allow many routes among many computers, so that a message could arrive at its destination by many possible ways, not just a single path. In 1973 the first international connec­tions were made with England and Norway. By 1977 many more interna­tional connections had been made—thus the name Internet.

With the many different kinds of computers being connected, engineers had to find a way for the computers to speak the same language. The solution developed was TCP/IP, the standard since 1983 and the standard language of the Internet. TCP/IP, for Transmission Control Protocol/Internet Protocol, is the standardized set of guidelines (protocols) that allow different computers on different networks to communicate with each other efficiently, no matter how they gained access to the Net, the topic of the next section.

5. Communications.

Text I. Communications

“Communications” refers to the electronic transfer of data. The kind of data being communicated is rapidly changing from analog to digital.

Communications is defined as the electronic transfer of data from one place to another. Of all six elements in a computer-and-communications system, communications probably represents the most active frontier at this point. We mentioned that, until now, most data being communicated has been analog data. However, as former analog methods of communication become digital, we will see a variety of suppliers, using wired or wireless connec­tions, providing data in digital form: telephone companies, cable-TV services, news and information services, movie and television archives, interactive shopping channels, video catalogs, and more.

^ Communication (1)

Communication is the process of exchanging information. People ex­change information using communication means. Communication has al­ways some purpose. Mass communication, for example, sends messages for masses of people.

The history of communication means is a long and interesting one.

Communication through electric media. At the beginning of the 19th cen­tury the electric revolution made great progress. By 1832 the telegraph had been invented. Wires crossed the continents and cables were put under the Atlantic Ocean. Some 40 years later (in 1876) the telephone was patented. Messages began to be transmitted over electrical currents carried by wires.

"Early radio". At the beginning of the 20th century it became possible to transmit messages without wires. Messages were sent by wireless telegraph that is now called "early radio". But modern radio became possible only when a vacuum tube had been invented (1906). Soon after the invention of tubes, radio receivers began to be widely used in the world.

^ Communication (2)

Television. Television was used experimentally as far as 1930. But its popular use began only some ten years later. And in about twenty years colour television became dominant over black-and-white.

Audio and video recordings are most popular means of communication today. Also popular are filming and photography.

^ High-technology revolution in electronics influenced the sphere of com­munication and greatly changed it. The new technology used for space ex­ploration influenced modern communication both in offices and home. It became possible for business people to communicate with their colleagues in faraway places.

Computers and word processors serve this purpose and are being widely used in many offices all over the world.

The new technology has also influenced communication in everyday life. For example, it became possible for people to receive television programs through cables. Modern cable is a complex wire system that makes it possi­ble to transmit a number of television signals at the same time.

People today also widely use videotape recorders to record television programs. One of the most interesting inventions of today is also the usage of satellites for video and audio communication. People can receive programs through using satellites.


Texts for tests Hardware. Input/Output hardware iconInput: 3n in Output: standart output

Texts for tests Hardware. Input/Output hardware iconInput: 3n in Output: standart output

Texts for tests Hardware. Input/Output hardware iconEnvironmental stochastic input-output model and its deterministic equivalent

Texts for tests Hardware. Input/Output hardware iconСпеціальність Семестр
Texts for tests Hardware. Input/Output hardware iconПрограма дисципліни
Об'єкт інформатики. Інформаційні технології. Предмет інформатики. Галузі застосування комп'ютера. Склад пеом. Технічні засоби (Hardware)....
Texts for tests Hardware. Input/Output hardware iconДокументи
2. /HUMAN...

Texts for tests Hardware. Input/Output hardware iconТема Архітектура комп'ютера
Об'єкт інформатики. Інформаційні технології. Предмет інформатики. Галузі застосування комп'ютера. Склад пеом. Технічні засоби (Hardware)....
Texts for tests Hardware. Input/Output hardware iconДокументи
1. /lec1 The reliability of counting devices.doc
2. /lec10...

Texts for tests Hardware. Input/Output hardware iconTexts for translating

Texts for tests Hardware. Input/Output hardware iconДокументи
1. /Control questions and tests/Control questions.docx
2. /Control...

Додайте кнопку на своєму сайті:

База даних захищена авторським правом ©zavantag.com 2000-2013
При копіюванні матеріалу обов'язкове зазначення активного посилання відкритою для індексації.
звернутися до адміністрації