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Starting electronics
Actually, it’s quite difficult to express a NAND gate’s operation
in words, but here goes: it’s a gate whose output Z is 1 when
NOT A AND NOT B AND NOT C is 1. Err… yeah, right!
A better way is to express it as the Boolean statement:
which, no doubt you have already worked out!
Haven’t you?
Simple, eh?
Earlier on I mentioned that all digital circuits can be made up
from the simplest of digital circuits — the inverter. I’m going
to prove that now; theoretically at first, then we can do some
experiments which show the fact practically.
By expanding the inverter circuit we first looked at back in
Figure 10.1 and the following circuits, we can easily create
other circuits. Figure 10.31, for example, is merely a transistor
operating in the same way that the inverter transistor circuit
of Figure 10.1 works.
It is, effectively, an inverter with three inputs to its base,
rather than just one.
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