PURPOSE: To obtain a display value rapidly and accurately by inputting pulse train signals such as a vehicle speed and a number of rotations while switching them and counting the period of respective pulse train signals so that the display value may be outputted from a memory circuit for every counted value.

CONSTITUTION: Input circuit 1 takes in pulse trains applied to input terminals Y1 to Yn while switching them. Logical operation circuit 2 performs a step to switch successively pulse train signals of a control unit, a step to count the pulse train signal period, a step to read a value corresponding to display conditions, a step to operate the difference between counted values, a step to dispkay values, etc. Memory circuit 3 stores values corresponding to display conditions which are obtained from the operation result of logical operation circuit 2. Memory circuit 4 stores the value on the way of operation or the operation result at every operation step of logical operation circuit 2. Driving circuit 6 gives display conditons to a display element, and display circuit 7 displays a value corresponding to pulse train signals.