For a while I've been using a pair of diodes (and a pull-down resistor to -5V) to connect the outputs of two gates together and get a combination of them. When this is done, the final output is equal to whichever gates output is higher. So far, several of the monadic gates and all of the two-input gates use this trick in order to arrange the final truth-table. This is called wired logic and is actually a "wired OR". In a binary system if one gate OR the other gate is high, the output will be high.

This can be turned around by reversing the diodes and changing the pull-down into a pull-up to +5V. This is a "wired AND". I've done a few initial tests and the result, even with three logic levels, is to always output the lower of the two gates. In other words:

Wired OR

- OR - = -

- OR 0 = 0

0 OR 0 = 0

- OR + = +

0 OR + = +

+ OR + = +

Wired AND

- AND - = -

- AND 0 = -

- AND + = -

0 AND 0 = 0

0 AND + = 0

+ AND + = +

This additional tool will make designing more complex circuits easier since I will be able to "build up" a truth table using wired OR, as well as "build down" a truth table using wired AND.

Incidentally, it occurred to me that I have developed a whole new class of digital circuits; Comparator-Diode Logic. Yay! Okay, I know a comparator is just a bunch of transistors and such, but still...