PARETO
Proceso 3 Producto
1.3.2.2. Eficacia
A modem is a device that translates a computer’s ones and zeros into audio tones, so that it can transmit information over the phone lines to other modems. The speed in which a modem can transmit and receive data is measured in bits per second (bps), or baud. For example, a 300-baud modem can transmit 300 bits per second. The most common way people use modems is to connect to the Internet. By the way, modem stands for modulator-demodulator.
Modems come in two basic flavors:
• Analog Modems: Computers store information digitally, while telephone lines transmit conversations and sounds. An analog modem converts a computer’s ones and zeros to tones than can then be transmitted over standard phone lines. Analog modems are limited to speeds of 56Kbps.
• Digital Modems: Use binary ones and zeros to transmit data like a computer. Digital modems can transmit information much faster than analog modems. Digital modems are often referred to as broadband modems.
Table 4-3: Modem Types and Speeds describes the most common analog and digital modems out there.
Figure 4-8
An internal modem plugs into an expansion slot inside a computer.
Figure 4-9
An external modem plugs into a serial port and sits outside a computer.
Figure 4-10 Most laptops have a built-in modem.
Figure 4-8
Figure 4-9 Figure 4-10
Chapter Four: Information Networks 111
Quick Reference Analog Modem:
• Converts a computer’s ones and zeros to tones that can then be
transmitted over standard phone lines. Analog modems are limited to speeds of 56Kbps.
Digital Modem:
• Uses binary ones and zeros to transmit data like a computer. Digital modems can transmit information much faster than analog modems.
PSTN, PSDN:
• Ordinary, everyday telephone network, limited to 56Kbps.
ISDN:
• An older broadband connection, twice as fast as a traditional modem at 128Kbps.
ASDL, DSL:
• Fast digital connection with speeds up to 8,000Kbps.
Cable:
• Fast digital connection with speeds up to 4,000Kbps.
Table 4-3: Modem Types and Speeds
Type Speed (in bps) Description
Analog
PSTN, PSDN 56K PSTN stands for Public Switched Telephone Network, and is nothing more than your everyday, ordinary telephone system based on copper wires. PSTN is often referred to as POTS, or plain old telephone service.
PSDN stands for Public Switched Data Network and is just another technical term for the telephone system in use today.
ISDN 56K to 128K One of the older broadband connections. It’s only twice as fast as a traditional modem and pretty much obsolete.
ADSL, DSL 256K to 8,000K ADSL modems take advantage of unused frequencies in the phone line, such as a pause in conversation. DSL modems are very fast; the problem is that you have to be close to a phone company in order to get DSL service.
Digital, Broadband
Cable 640K to 4,000K A cable modem is the fastest modem you can buy for home use. The problem is your cable company has to offer cable Internet access in order to use it.
112 Computer Basics
Chapter Four Review
Lesson Summary
Introduction to Networks
• LAN: Stands for Local Area Network and connects computers in the same geographic area or building, using cables.
• WAN: Stands for Wide Area Network and connects computers across a large geographic area.
• Peer-to-Peer/Workgroup: Files and resources are shared on every computer. Easier to setup but very insecure.
• Client/Server Network: Files are stored on a single central computer, or server. More secure and expensive.
The Internet
• Internet: The Internet is the largest computer network in the world and connects millions of computers.
• World Wide Web: A way of accessing information over the Internet.
Intranets and Extranets
• Intranet: A miniature version of the Internet that works on a network within a company or organization.
• Extranet: A miniature version of the Internet that allows access to authorized outside users, such as business partners.
Telephones and Networks
• An analog modem converts a computer’s ones and zeros to tones that can then be transmitted over standard phone lines. Analog modems are limited to speeds of 56Kbps.
• A digital modem uses binary ones and zeros to transmit data like a computer. Digital modems can transmit information much faster than analog modems.
• PSTN, PSDN: Ordinary, everyday telephone network, limited to 56Kbps.
• ISDN: An older broadband connection, twice as fast as a traditional modem at 128Kbps.
• ASDL, DSL: Fast digital connection with speeds up to 8,000Kbps.
• Cable: Fast digital connection with speeds up to 4,000Kbps.
Chapter Four: Information Networks 113
1. A LAN connects computers in the same building or facility. (True or False?) 2. What does LAN stand for?
A. Linked Area Network B. Lots of Anarchy and Nonsense C. Local Area Network
D. Linked Applications Node
3. An Intranet is a miniature version of the Internet that allows access to authorized outside users, such as business partners. (True or False?) 4. Which of the following modems is the slowest?
A. ISDN B. DSL C. Cable D. Standard
Quiz Answers
1. True. A LAN connects computers in the same building or facility.
2. C. LAN stands for Local Area Network.
3. False. An Extranet is a miniature version of the Internet that allows access to authorized outside users, such as business partners
4. D. A standard modem is much slower than the other digital modems.
Chapter Five:
Introduction to Windows XP
Chapter Objectives:
• Start and log on to Windows
• Understand the Windows XP screen
• Understand the new Windows XP interface
• Use the mouse to: point, click, double-click, right-click, click, and drag
• Use the keyboard
• Exit Windows and turn off the computer
Welcome to Windows XP! If you’re new to Windows, or to computers altogether, you’re starting at the right chapter. This chapter covers the “bare-bones” basics about learning how to start your computer and load Windows. You’ll learn how to operate the mouse by clicking, double-clicking, clicking and dragging, and right-clicking. You’ll also learn about your computer’s keyboard and what those cryptic-looking keys are used for. Finally, you’ll learn how to exit Windows and shut down your computer.
Before we start, take a deep breath and relax. You may find this difficult to believe, but computers aren’t nearly as difficult and complicated as you probably think they are. No matter what your previous experience with computers has been, this chapter assumes you’re the most computer-illiterate person in the world and keeps everything as simple as possible. Actually, you’re probably going to find that some of the lessons in this chapter are a little too easy.
When you come across something you already know how to do, go ahead and skip the lesson (unless you’re in a classroom of course—then go ahead and show everyone what a computer whiz you are!).
Ready? Did you take that deep breath? Then turn the page and let’s get started!
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Prerequisites• Windows XP installed on the computer.