local echo

    (Obsolete: "half-duplex") A mode of
   operation of a communications program or device in which it
   displays the characters the user enters at the same time as it
   sends them to the remote system.

   In communications between computers or computing processes,
   particularly those involving human keyboarding and/or reading,
   duplex came to mean the re-transmission of a keyboard
   character to the output display.

   Early input device such as the Teletype ASR-33
   teleprinter, being descended from the electric typewriter,
   printed all input characters as they were typed (i.e. they did
   local echo).  Local echo was typically optional on the video
   terminals that replaced them, and usually disabled in favour
   of remote echo.  A disadvantage of local echo is that it
   will continue, even when the communication circuit has failed,
   which can be misleading.

   (2000-03-30)