Bluetooth

Okay, you now have a computer. There it is in front of you, and you're sitting in front of it, looking at a page on the World Wide Web. You have learned how to use your computer to browse through the Information Highway which is the Internet, and to find this and other pages on a bewildering array of topics.

But is this all you want your computer to do? For some people this is enough, and the computer need do nothing more. However, many people want to do more with their computers, and more get tired of their original activity and want to turn to something new. The question is, What? The computer is a general-purpose tool with many uses, so the primary limits on what it does are set by the choices of its user -- you.

There are four basic categories of activities that you can pursue with regard to computers. Each is necessary to all of the others, but different interests and disciplines are needed in the different categories. By following the links below you can get further information on each type of computer category. The four general computer categories are:Computer Users

By far the largest single group of people dealing with computers consists of those who use them to perform various tasks. These are the people who will purchase and use commercial programs such as word processors, spreadsheets, database managers, accounting programs, and many others. Such programs are packaged and available for sale. They must be installed on the computer, but then can be called up and run by any user.
Computer Programmers

Some people start out wanting to do more with a computer than just running existing programs. Others are users who find it necessary or desirable to create a needed application that does not yet exist. And many users want to be able to automate processes they have to go through regularly. All such activities require the development of a new program for the computer. Such a program can be very simple or extremely complex, but it always has several elements in common with all other programs.
Computer Technicians and Service People

Computers are machines, and any machine can break. Therefore, there will be a need for people to repair them. In addition, it is a common requirement to upgrade a computer. This may involve adding more memory, installing a new interface card, installing a better processor, or something else. A computer service technician needs to know something of the inner workings of the computer, and often needs to know a certain amount of electronics as well. The more such a technician wants to do, the more electronics and digital logic he or she needs to know.
Computer Designers

At the top of the list of those requiring technical skills and knowledge we have the relatively small number of people who actually design new computers and their primary components. These are the people who actually design new and ever more powerful processors, video display components, general and specialized chipsets, and even whole computer systems. Anyone seeking to design computers or computer systems will need an extensive knowledge of electronics, digital logic, semiconductor physics, and a number of related subjects.

# Twisted pair - Wire twisted to avoid crosstalk interference. It may be shielded or unshielded. #* UTP-Unshielded Twisted Pair. Normally UTP contains 8 wires or 4 pair. 100 meter maximum length. 4-100 Mbps speed. #* STP-Shielded twisted pair. 100 meter maximum length. 16-155 Mbps speed. Lower electrical interference than UTP. # Coaxial - Two conductors separated by insulation such as TV 75 ohm cable. Maximum length of 185 to 500 meters. ## Thinnet - Thinnet uses a British Naval Connector (BNC) on each end. Thinnet is part of the RG-58 family of cable*. Maximum cable length is 185 meters. Transmission speed is 10Mbps. Thinnet cable should have 50 ohms impedance and its terminator has 50 ohms impedance. A T or barrel connector will have no impedance. Maximum thinnet nodes are 30 on a segment. One end of each cable is grounded. ## Thicknet - Half inch rigid cable. Maximum cable length is 500 meters. Transmission speed is 10Mbps. Expensive and is not commonly used. (RG-11 or RG-8). A vampire tap or piercing tap is used with a transceiver attached to connect computers to the cable. 100 connections may be made. The computer has an attachment unit interface (AUI) on its network card which is a 15 pin DB-15 connector. The computer is connected to the transceiver at the cable from its AUI on its network card using a drop cable. Maximum thicknet nodes are 100 on a segment. One end of each cable is grounded. 3. Fiber-optic - Data is transmitted using light rather than electrons. Usually there are two fibers, one for each direction. Cable length of 2 Kilometers. Speed from 100Mbps to 2Gbps. This is the most expensive and most difficult to install, but is not subject to interference. Two types of cables are: 1. Single mode cables for use with lasers has greater bandwidth and costs more. Injection laser diodes (ILD) work with single mode cable. 2. Multimode cables for use with Light Emitting Diode (LED) drivers. All signals appear to arrive at the same time. P intrinsic N diodes or photodiodes are used to convert light to electric signals when using multimode.

{| ! Media ! Distance(meters) ! Speed ! Approx Cost/station | UTP 100 4-100Mbps $90 STP 100 16-155Mbps $125 Thinnet 185 10Mbps $25 Thicknet 500 10Mbps $50 Fiber 2000 100Mbps-2Gbps $250 (multimode) |}