Control begins when one condition determines what another part of a system may do.

A switch directs current. A valve directs flow. A multiplexer directs information. Each device turns a choice into a physical consequence.

Connect many such choices and the system acquires structure: one result selects the next action, regulates a process, or changes the path that follows.

Computation grows from that organized control. Its apparent complexity rests on a field of simple decisions whose connections create memory, arithmetic, communication, and behavior.

Continue from a single act of control into a general architecture of computation.