| 摘要 |
PURPOSE: An input/output apparatus is provided to improve an execution speed, and to efficiently execute a read/modify/write operation by reducing an unnecessary access to a memory. CONSTITUTION: A previous open-drain form input/output device performs a feedback of signal outputted from the second latch(L2). The signal passes through the third triple buffer(T3) synchronized to an inverse signal of a control signal. Another path read from an internal data bus is added. In case that a read/modify/write operation is performed, '1' is written to an input/output port. '0' is written by an external logic again. In case that the input/output port is read again, and an output value is toggled and outputted, a read path is cut off by the control signal. A write path is performed through the second latch(L2).
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