| 摘要 |
<p>PURPOSE:To attain effective utilization of external leading terminals by providing a microcomputer comprising an integrated circuit having >=2 oscillating circuits and the external lead terminal for connecting the oscillating circuits so as to use a data input/output terminal and the external lead terminal for connecting the oscillating circuits in common. CONSTITUTION:When a control signal (a) is logical 1, that is, externally mounted components, 6, 9, 10, 12 for the oscillating circuit are connected, a clocked inverter 21 is activated to attain oscillation. An output of NOR circuits 24, 27 is logical 0, then no effect is given onto the operation of the oscillating circuit. Further, X1 and X2 output data are made ineffective. Moreover, X1, X2 input data are fetched to a CPU (central processing unit) as required only from a gate at the post-stage of inverters 22, 25. When the control signal (a) is logical 0, the clocked inverter 21 is inoperative and no effect is given onto the terminals X1, X2. While the output data of the input/output terminals X1, X2 are made effective, the X1, X2 output data are made logical 1 in fetching external data.</p> |
