DISPLAY CONTROLLER

PURPOSE: To display a message for realizing an intended operation, in addition to provide an alarm of erroneous operation or an operational procedure, by additionally providing an operation memory section, an operating condition memory section, etc. CONSTITUTION: An external unit 1 is operated on various keys at a key input section 4 and the operation results are stored at a set condition memory section 5 while past key operation is stored at an operation memory section 7. An operating condition memory section 8 stores the operating conditions of the external unit 1 while a message memory section 6 stores the content of message and a display section 3 presents the content of operation. A processing section 2 makes a decision whether the various keys at the key input section 4 are operated erroneously or not or an intended operation is set or not based on the contents at the set condition memory section 5, the operation memory section 7 and the operating condition memory section 8. A message corresponding to the decision results is then selected from the message memory section 6 and delivered to the display section 3.