3-1
Issue 2 May 1995
3
This chapter highlights some of the basic functions and
commands necessary to operate your modem. Whether you
consider yourself a novice or an experienced user in data
communications, you may want to read through some of the
examples to become familiar with your modem’s operation.
For information on more advanced concepts such as altering
data rates, error control, data compression, and flow control, see
Appendix E,
Advanced Modem Concepts.
What is a Modem?
A modem is a piece of equipment that allows your computer to
communicate over telephone lines with other computers. Picture
the modem as a telephone for your computer — it performs
many of the same functions as a telephone, such as dialing,
answering calls, and hanging up.
Information is sent over telephone lines in a format called
analog. Computers, however, communicate information in a
format called
digital. The modem’s job is to translate the
information between the two formats. A modem converts digital
information from a computer into analog so that it can be sent
over a telephone line to another modem. The receiving modem
then translates the information back into a digital format so that
the receiving computer can use it (see Figure 3-1).
This process of modulating (converting digital to analog) and
demodulating (converting analog to digital) a signal gives us the
acronym, modem.
