Communications circuit

Data terminal equipment (DTE)

A Computer or business machine that provides data in the form of digital signals as it's output.
eg ; Terminals, PC's , Computers.

Data communications equipment (DCE)

The equipment that provides the functions to establish, maintain and terminate a connection.
Provides the signal conversion required for communication between DTE's and the telephone line, or data circuit.
Example
Modems, Multiplexors, Concentrators, Front End Processors

Communications medium

Telephone Line, or Data Circuit
Example
Cables, Wires, Telephone cables, Microwaves, Radio waves

Interface

Software between;

• The DTE, and DCE
  Communications Programs
  Operating Systems
  Firmware (Read-only memory)

Host

• Refers to the computer system that performs the Processing for a DTE (Data Terminal Equipment).
  For example
  A multiuser Unix server does the processing for attached terminals.

Terminal

• Data Terminal Equipment that is able to receive and send digital data.
  For example
  A PC running an appropriate terminal interface can act as a terminal.

Local

• Refers to the physical proximity of some device, in that DCE (Data Communication Equipment) is not required to access the device.
  For example
  In a multiuser system a terminal is directly connected via cable to a server.

Remote

• Refers to the physical proximity of some device, in that DCE (such as a modem or NTU) is required to access the device.
  For example
  A terminal in a local bank branch is connected to a central server that may be in another city or country.