POSEIDON
Any computer that forms part of a control system-whether
completely automatic or partly human-must 
work at the same speed as the control system.  It must
perform its calculations or data processing fast 
enough for the results to be available at the required
instants in the action of the control system. 
 This known as working in "real time."
CACM March, 1962
Wheeling, R. F.
