Page 85 - Bebop to The Boolean Boogie An Unconventional Guide to Electronics Fundamentals, Components, and Processes

66 H Chaptersewen

Tertiary Logic
And finally, for reasons that become a little involved, communications
theory tells us that optimal data transfer rates can be achieved if each data
element represents three states. Now engineers wouldn’t be the guys and gals
they are if they weren’t prepared to accept a challenge, and some experiments
have been performed with tertiary logic. This refers to logic gates that are based
on three distinct voltage levels. In this case, the three voltages are used to
represent the tertiary (base-3) values of 0,1, and 2, and their logical equivalents
FALSE, TRUE, and
However, while it’s relatively easy to use transistors to generate two distinct
voltage levels, it’s harder to generate a consistent intermediate voltage to
represent a third value. Similarly, while it’s relatively easy to use transistors to
interpret (detect) two voltage levels, it’s harder to interpret a third, intermediate
value.7 Additionally, creating and using an equivalent to Boolean algebras that

works with the three logic states FALSE,
Apropos of nothing at all, man has TRUE, and MAYBE is enough to make

even the strongest among us quail.
Thankfully, tertiary logic is currently of
~
academic interest only (otherwise this
book might have been substantially
longer). Still, there’s an old saying

“What goes round comes around,” and
it’s not beyond the realm of possibility
L..UL “C C..CC.LU..
for every purp that tertiary logic or an even bigger
relative will rear its ugly head sometime
in the future.

6 A tertiary digit is known as a “trit”.
7 Actually, if the truth were told, it’s really not too difficult to generate and detect three voltage
levels. The problem is that you can’t achieve this without using so many transistors that any
advantages of using a tertiary system are lost.
8 Boolean Algebra is introduced in Chapter 9.