So Applications

Result 0 0 0 1

CPL (NOT) 1110

Result 0 111

Result 0 110

Example 1. Binary Digit Calculations

Not (CPL) Gate, Generic type 7404, 6 gates per IC.

AND Gate, Generic type 7408. 4 gates per IC.

OR Gate, Generic type 7432, 4 gates per IC.

First Digit -Second Digit ■

XOR Gate, Generic type 7486, 4 gates per IC.

First Digit -Second Digit •

NAND Gate, Generic type 7400, 4 gates per IC.

NOR Gate, Generic type 7402, 4 gates per IC.

NOR Gate, Generic type 7402, 4 gates per IC.

XNOR Gate, Generic type 74266, 4 gates per IC.

txample 2. Equivalent Integrated Circuits input 7427 NOR gate, etc.—which have the effect of applying the logic function to all inputs. The 13-input 74133 NAND gate would perform this function: Input 1 AND Input 2 AND Input 3 AND Input 4 AND Input 5 AND Input 6 AND Input 7 AND Input

8 AND Input 9 AND Input 10 AND Input 11 AND Input 12 AND Input 13 = Result, then CPL (NOT) the result. It does this, incidentally, in less than 15 billionths of a second, 30 times faster than the Z-80 chip could perform the same function!

Still other ICs may combine gates, such as the 7464 (see Fig. 3). This gives the single-digit result of this complete logic equation:

Y = NOT ((A AND B AND C AND D) OR (E AND F) OR (G AND H AND I) OR (J AND K))

Okay, stay with me. Like they say in those ads for clothing patterns, if I can sew, you can sew. Same goes for this digital hardware; but put me Inside a ham radio, and I'm thoroughly lost. This digital stuff is easy, however, since it just involves transferring the logical theory you already know into a different form, a form that looks like electronics. By way of tangential explanation, let me digress a bit about functional fixedness. We all consciously tend to limit our vision or imagination, mostly because it's the easiest way to make sense out of the world around us. That's okay for basic survival, but consider: A spoon alone is great for soup, but if used with a dash of human imagination, two spoons can make music. Who thought of that? Not the same person who turns junk car bumpers into sculpture, but the principle is about the same. Here's another thought: Until a new timing belt arrives, my printer's carriage return functions because I have nylon string attached to the print head, looped over a pulley, and weighted down with a paper punch. It works, with no fancy elec-tronia. Think about this: If thumbs were the key factor in the evolution of humans from lower animals, then binary is a truly unnatural number system. If It's unnatural, then no matter how it's transformed, it's legitimate if we need it that way. Now back to digital logic.

Consider this listing:

LD A,VALUE

0 0

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