SUPER-IMPOSE CONTROL CIRCUIT

摘要

PURPOSE:To improve the efficiency of access from a CPU to a storage part storing character pattern information to be displayed on a display device by forming a CPU timing generating part and a display timing generating part independently. CONSTITUTION:When the CPU2 is to write or read out data in/from the storage part 1, a signal generated by a CPU timing generating part 6 is used. Even if a display control part 3 has completed display and stopped the operation of a display timing generating part 7, the CPU timing generating part 6 holds the operating state as it is. When an external cynchronizing signal is inputted and the display timing generating part 7 starts the operation again, the CPU timing generating part 6 temporally stops by a signal from a timing generating part 5 and then starts to operate instantaneously and synchronously with the display timing generating part 7. Consequently, the CPU can write or read out data in/ from the data storage part efficiently almost without waiting time.