| 摘要 |
The invention is concerned with the method which reduces the number of required I/O terminals of microcomputer by using the data selector and combining the lock key & the matrix key. In the method using a data selector (2), in order to distinguish four inputs and two outputs of a microcomputer (1) must be input to the data selector and one output of the data selector must be input to the microcomputer. Therefore, three input and output terminals of the microcomputer are required. Generally speaking, to distinguish external states from n terminals of microcomputer, one terminal must be used to the output of data selector (2) and the remaining terminal must be used to distinguish the external state.
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