### equipment:

Modem
* Describe the operation of modems.
* Many modems have two jacks, one for the telephone line and one for a telephone handset.
* Most modems have special electronic components that do 'error correction'.
* Some modems are cards that fit into slots inside the computer
  - emit a series of clicks when waiting for a dial tone, dialing, or waiting for an answer
  - have both a phone and a line socket
  - use data compression to achieve faster data throughput
* There are many types of communication software that can be used with modems.
* allow computers to communicate with one another via the telephone lines
  - send and receive data over phone lines
  - transmit information to one another via an ordinary telephone line
  - data to be transmitted over voice-grade telephone lines
  - for communication between computers at remote sites
  - two computers literally to 'talk' back and forth to each other
* also convert analog signals from telephone lines into digital signals for computer use
  - use changes in sound, to transmit digital data
* are a competitive market
  - high speed, cheap and easy way to communicate with people and is very popular
  - popular means to connect home computers to the internet
  - switched technology, and the only analog technology in use today
  - also an inefficient use of the telephone network
* are devices that connect the computer to a phone line
  - let computers send data over phone lines
  - use standard analog phone lines to transmit data
  - which allow digital data signals to be transmitted across an analog link
  - electronic equipment
  - far more sensitive than human ears
  - now an integral part of most office computers and many home computers
* are the basic device used to convert messages to and from different computers
  - devices that let computers talk to each other over telephone lines
  - primary way most computer users connect to outside networks such as the Internet
* can transmit computer information around the world.
* come in all sizes and shapes
  - with the capacity to transfer information at various speeds
* connect computers over telephone lines.
* convert data into sound so that it can be sent through the phone system
  - digital signals from a computer into analog signals in the telephone frequency range
* differ in the way they enable data compression.
* enable computers to be connected so they can exchange information
  - transmit digital data over the Networks
* have a speed rating which measures how fast data can be communicated in bits per second
  - problems
* includes circuits
  - electron tubes
  - resistors
  - sections
  - vacuum tubes
* is electronic equipment
* operate at frequencies outside the range of human hearing.
* rely on serial communication to send data over telephone lines.
* still account for the majority of Internet connections.
* tend to generate heat, which can cause flaws in the electronic components.
* translate computerized data into signals that travel through phone lines
  - digital computer information into analog signals used over phone lines
* transmit information at various speeds known as baud rate.
* use IRQs to signal the computer that data has been received or sent
  - different tones to represent different bits of data
* used in the dial-up telephone network have two wires, the same as a standard telephone set.
* vary in the speed with which they can transmit data between computer and internet.
* work on analog, or sound, signals.