Physical Types

Analog

The analog side is measured in baud where 1 baud is one change in the signal per second. Most people use bps and baud as though they were the same. For speeds of 2400 bps and under, this is true, but is it not so for the higher speeds where more than one bit is transmitted per signal change.

There are three physical types of modems:

External which plugs into a serial port on the back of the computer

Advantages:	Can be moved to a different computer easily. Does not take up a slot inside the computer. Lights on front are visible to show what the modem is doing.
Disadvantages:	Takes up deskspace. Adds more cables to the tangle.

Internal
where the phone line plugs directly into card through the back of the computer

Advantages:	Saves deskspace. Saves a cable.
Disadvantages:	Requires an internal peripheral slot. (They get filled up.) Must use software display to see the lights that show what the modem is doing.

Acoustical
(Very old) The telephone handset is placed into the device, which is connected to the computer. Not many of these around any more.You have to have an old-style telephone, too.

Advantages:	Can use a phone without having to move the phone wire.
Disadvantages:	Bulky Connection much more prone to static and interference. Only a standard handset will fit.

Дата добавления: 2014-12-23