Newnes Digital Logic IC Pocket Book

6

Buffer, Gate, and Logic IC Circuits

Earlier chapters of this book explained TTL and CMOS principles and basic usage rules, and looked at the ‘74’- and ‘4000’-series of ICs and at various sub-members of these families. The present chapter carries on the ‘digital ICs’ theme by showing practical ways of using TTL and CMOS buffers, inverters, and logic gate ICs.

Logic Gate Symbology

The eight best known types of logic ‘gate’ are the buffer and the NOT, OR, NOR, AND, NAND, EX-OR and EX-NOR types. Many different symbols can be used to represent each of these eight basic logic gate elements. Figure 6.1 shows four different families of symbols that are widely used in various parts of the world today; of these, the American MIL/ANSI symbols are by ...