Terminal node controller

Originally developped by Doug Lockhart, VE7APU, of Vancouver, British Columbia, a TNC is a device is used by amateur radio operators to convert ASCII characters to modulated tones and vice-versa, this mode of operation is called packet radio. A TNC usually includes software that allows the unit to function as a BBS (bulletin board station) or to receive messages while the computer is not operating.

Like email, a "packet" of data contains the callsign of the sender and intended recipient, along with the content of the message. A long text message will be converted to several "bursts" or packets of information by the TNC.