| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a microcomputer which controls the operation of an external extension interface in an external memory extending mode to output no signal to be noise to the external extension interface at the time of utilizing an internal memory and utilizing the external extension interface as an external extension I/O interface at the time of not using an external extension memory. SOLUTION: An identification signal expressing whether a decoded address indicates the internal memory or the external extension memory is outputted (step 46) and when an internal memory access signal is outputted, a signal from the external extension interface to outside is disconnected. In addition, the state of the external extension interface is switched to the state of the external extension memory interface or the state of an I/O interface according to the access of CPU.</p> |
