PURPOSE: To display 1st and 2nd video images without a blank automatically corresponding to the 1st video image written in an optional range by storing the end of write of the 1st video signal by a latch circuit and allowing a comparator decoder circuit to discriminate the readout over the write and selecting the display of the 2nd video signal.
CONSTITUTION: A control signal output of a comparator decoder circuit 16 resulting from a write address and a readout address latched by a latch circuit 15 is used for changeover control of a video signal switching circuit 12. The latch circuit 15 latches and stores an address just before the write address is reset and the comparator decoder circuit 16 compares the quantity between the readout address and the latched address and outputs a switching control signal when the readout address is larger than the latched address. Thus, the 1st and 2nd video signals are switched and displayed without a blank corresponding to the 1st video signal written in an optional range.
OISHI YOSHINOBU
KAMATA SHINYA
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