An abbreviation of Modulator/Demodulator, a device used to transmit data via phone line.

The name stems from the fact that it modulates an audio signal according to the stream of bits sent to it by a computer so that it can be sent across a phone line. Meanwhile, it detects modulation of the incoming signal to reconstruct the original stream of bits it was made from, which is then sent to the computer. Thus, you can network two computers with MoDems via a phone connection.

AddToMe: does this still apply to CableModem?s?

Most modern MoDems, so-called WinModems, do not contain the hardware necessary to perform all of this operation. Instead, they rely on the host CPU for much of the signal processing. Because the software to do this is part of the MoDem driver, and many vendors write drivers only for MicrosoftWindows, some WinModems cannot be operated under Linux.