| 摘要 |
A programmable logic circuit is formed by at least one gate. The gate is formed by four logic circuits, one being a first exclusive NOR circuit having a first input, a second input and an output. A second exclusive NOR circuit having a first input, a second input and output is provided, the first input of the second exclusive NOR circuit being coupled to the first input of said first exclusive NOR circuit. An AND circuit having a first input, a second input and an output is also provided. The first input of the AND circuit is coupled to the output of the first exclusive NOR circuit and the second input of the AND circuit means is coupled to the output of the second exclusive NOR circuit. A third exclusive NOR circuit having a first input circuit, a second input circuit and an output circuit is provided the first input circuit of the third exclusive NOR circuit is coupled to the output of the AND circuit. The gate can selectively function as an OR, NOR, AND and NAND circuit depending on ONE and ZERO signal levels applied to the respective second inputs of the second and the third exclusive NOR circuits as program variables. One of the variables is applied to the first input of the first exclusive NOR circuit and to the first input of the second exclusive NOR circuit, another variable being applied to the first input of the second exclusive NOR circuit. By connecting the second input of the second exclusive NOR circuit to one of the inputs of the first exclusive NOR circuit, the logic circuit will operate as an exclusive OR or exclusive NOR circuit.
|
