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PneumADDic II • Masterpiece 4 189

PneumADDic II uses air pressure to change the location of the piston head, and
therefore remember a new value.The pressure inlets for the Piston sub-assemblies play
the role of the value input for our Carry Memory.The RCX only allows pressure
through to the Carry Memory inputs at certain times during the addition process. When
pressure is applied, the Carry Memory remembers the new value.The pneumatic switch,
which you remember has its lever position controlled by the pneumatic piston, acts as the
memory output of Carry Memory. Pressure applied to the pneumatic switch is routed to
the switch’s ports based on the direction the lever is leaning.
It takes time for the pneumatic adding circuit to calculate the answer. When new
values are fed to the circuit via the RCX and motorized pneumatic switches, the changes
affect the gates connected to the motorized switches. When the outputs of the first gates
change, they affect the next gates in the circuit. When these outputs change, they affect
the next gates and so on. We must let all those changes happen before we know that the
Carry calculated by the pneumatic adding circuit is correct. Only then can we make the
Carry Memory remember the Carry value, by applying pressure to the inlet of the switch
that drives the Carry Memory.

Carry Memory Step 0

Carry Memory Step 1