The scenario
A digital systems student must implement an elevator controller as a combinational logic circuit from a natural-language specification.
What is in this drawing
Read the decisions behind it.
01
Each direction output is the OR of all (request, position) pairs that imply movement in that direction.
02
DOOR_OPEN asserts when the elevator is at a floor that has an active request.
03
Pure combinational design keeps the schematic flat; real elevators add a state machine for queued requests.
Add D flip-flops to queue multiple simultaneous floor requests; extend to N floors by adding more input pairs.
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