Computer Education

INTERNET
Uses of the Internet
Internet Access
How Information Travels Over the Internet
Network Names and Addresses
Client/Server Architecture
Electronic Mail and News Groups
Other Internet Applications
Bandwidth
History
The Future of the Internet

Computer Memory
Internal RAM
Internal ROM
External Memory
Magnetic Media
Optical Media
Magneto-Optical Media
Cache Memory

HISTORY
Beginnings
First Punch Cards
Beginnings
Precursor to Modern Computer

TYPES OF COMPUTERS
Digital and Analog
Range of Computer Ability

NETWORKS

PROGRAMMING LANGUAGES
Machine Language
Assembly Language
High-Level Languages
FLOW-MATIC
FORTRAN
BASIC

HOW COMPUTERS WORK
Operating System
Computer Memory
Bus
Input Devices
Central Processing Unit
Output Devices

HOW A CPU WORKS
INTRODUCTION
Function
Branching Instructions
Clock Pulses
Fixed-Point and Floating-Point Numbers

HISTORY
Early Computers
Transistor
The Integrated Circuit

Internet Access


The term Internet access refers to the communication between a residence or a business and an ISP that connects to the Internet. Access falls into two broad categories: dedicated and dial-up. With dedicated access, a subscriber’s computer remains directly connected to the Internet at all times through a permanent, physical connection. Most large businesses have high-capacity dedicated connections; small businesses or individuals that desire dedicated access choose technologies such as digital subscriber line (DSL) or cable modems, which both use existing wiring to lower cost. A DSL sends data across the same wires that telephone service uses, and cable modems use the same wiring that cable television uses. In each case, the electronic devices that are used to send data over the wires employ separate frequencies or channels that do not interfere with other signals on the wires. Thus, a DSL Internet connection can send data over a pair of wires at the same time the wires are being used for a telephone call, and cable modems can send data over a cable at the same time the cable is being used to receive television signals. The user usually pays a fixed monthly fee for a dedicated connection. In exchange, the company providing the connection agrees to relay data between the user’s computer and the Internet.

Dial-up is the least expensive access technology, but it is also the least convenient. To use dial-up access, a subscriber must have a telephone modem, a device that connects a computer to the telephone system and is capable of converting data into sounds and sounds back into data. The user’s ISP provides software that controls the modem. To access the Internet, the user opens the software application, which causes the dial-up modem to place a toll-free telephone call to the ISP. A modem at the ISP answers the call, and the two modems use audible tones to send data in both directions. When one of the modems is given data to send, the modem converts the data from the digital values used by computers—numbers stored as a sequence of 1s and 0s—into tones. The receiving side converts the tones back into digital values. Unlike dedicated access technologies, a dial-up modem does not use separate frequencies, so the telephone line cannot be used for regular telephone calls at the same time a dial-up modem is sending data.

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