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162 Masterpiece 4 • PneumADDic II

in pneumatics by hooking up the hoses from the output of one gate to the inputs of
another gate reversed from the conventional way.

Table 1.5 Truth Table for the NOT Operator

Input Not
0 1
1 0

In the gates of PneumADDic II when the pneumatic switch lever is flipped to the
left, it means that the switch is outputting a 0, and when it is flipped to the right it means
the switch is outputting a 1.

■ When the lever is flipped to the right, the pressure is forced out the left port; in
these situations, I always hook light gray tube to the left port of the gate’s pneu-
matic switches and normally hook this to the base of the piston it is driving.This
way the piston expands when the switch outputs a 1.
■ When the lever is flipped to left, pressure comes out the right port; in these situ-
ations, I always hook the dark gray tube to the right port of a gate’s switch and
normally hook this to the top of the piston. When the switch outputs a 0, the
piston contracts.

To NOT a value is to convert a 0 to 1, or 1 to 0. In the case of our pneumatics, if we
want to NOT the input of a gate, we simply reverse the position of the previously
described hoses to the piston.This is to say that we swap the light gray tube and dark gray
tube connections from the standard previously described configuration.When the switch is
outputting a 0, pressure is forced through the dark gray tube, and sent into the base of the
piston causing it to expand.When the switch is outputting a 0, the pressure is forced
through the light gray tube, and sent into the top of the piston, causing it to contract.
Before we start discussing how we combine these gates to perform binary arithmetic,
let’s take time to build the gates themselves so you can play with them and get a feel for
how they work.

NOTE

To reiterate, in reversing the connections (pneumatic hoses) we can NOT the
inputs of a gate. This is the reverse of the normal situation where light gray
pneumatic tubing is used to make the piston expand, and dark gray pneumatic
tubing is used to make the piston contract.