Unformatted text preview: Binary Logic Gates
CHAPTER 3 3inputAND gate Fig. 3‘20 Substituting NAND gates. gates would be wired to perform the logic
function. The chart in Fig. 320 need not be
memorized. but it may he referred to as
needed in your future work in digital elec
tronics. 39 GATES WITH
MORE INPUTS Until now we have used gates that have had
only two or less inputs. But often we shall
need gates with more than iust two inputs.
Figure 321tal shows a 3input AND gate.
The Boolean expression For the 3input AND gate is A B C = Y, as illustrated in Fig.
321(b). All the possible combinations of
inputs A, B, and C are given in the truth table
in Fig. 321(c); the outputs for the 3input
AND gate are tabulated in the right column of
the truth table. Notice that with three inputs
the possible combinations in the truth table
have increased to eight. How could you produce a 3input AND
gate as illustrated in Fig. 321 if you have only
2input AND gates available? The solution is
given in Fig. 32.2(a). Note the wiring of the
2input AND gates on the right side of the dia
gram to form a 3input AND gate. Figure 17 ...
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 Fall '05
 Myer,B

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