In Computing
In computing, an echo is the printing or display of characters (a) as they are entered from an input device, (b) as instructions are executed, or (c) as retransmitted characters received from a remote terminal. In computer graphics, an echo is the immediate notification of the current values provided by an input device to the operator at the display console.
Some information from Federal Standard 1037C and from MIL-STD-188.
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