| 摘要 |
PURPOSE:To easily miniaturize a device and to reduce its cost by adopting a serial interface system, and using four pieces (for a power source, a synchronizing signal, and a data line) of signal pins. CONSTITUTION:Two pieces of power source use pins, one piece of synchronizing signal use pin and one piece of data line use pin are provided as interface use signal pins on a ROM side, and when the synchronizing signal is in a high level, the ROM is non-activated, and when said signal is in a low level, the ROM is activated, and by only a variation of a synchronizing signal pulse, an address of a data to be read out, in the ROM is determined, the data is started to send out serially by a unit of one byte or two bytes by one pulse of the synchronizing signal, and the read-out data and a clock generated in the ROM side are synthesized and transferred serially by a data line. In such a way, the cost of a ROMIC can be reduced, and also, the device is miniaturized.
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