| 摘要 |
PURPOSE:To increase the degree of freedom of the design by selecting positive or negative logic of the circuit so as to design, e.g., a program or a gate circuit without taking the state of a controlled circuit into account. CONSTITUTION:In constituting a positive/negative logic selecting means by an exclusive OR circuit 304, with a terminal 305 pulled up, ports 302-0-302-3 go all to a low level at the application of power and with the terminal 305 connected to ground, the ports 302-0-302-3 go all to a high level at the application of power. Thus, in case of the titled circuit used for output ports of a control circuit used frequently for a relay, a plunger or a clutch, the terminal 305 is pulled up by a resistor R401 so as to prevent a load such as a relay from being driven at the application of power.
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