Output circuit having capability of keeping logic state of signal sent between logic circuits

摘要

An output circuit is intended to be connected to any one of the circuits of a positive logic and a negative logic without having to initialize such a device as a register connected thereto. The output circuit is arranged to output a signal from a first logic circuit to a second logic circuit so that the first logic circuit is connected to an internal input terminal and the second logic circuit is connected to an external output terminal of the output circuit. The output circuit includes a logic state checking unit, a state storing unit, and a logic converting unit. The logic state checking unit serves to check the logic state of the external output terminal when initializing the first logic circuit. The state storing unit stores the checked logic state. The logic converting unit serves to compare the stored logic state of the output terminal with a logic state of a signal at the input terminal sent from the first logic circuit and determine the logic level of a signal to be fed to the second logic circuit.