Sequential circuits: clock

"Without time, everything would happen at once."

- Anonymous

Clock

Outside world: way to tell time

Computer: think of a metronome (number of beats, or cycles, per minute)

Measured in MHz or Ghz (millions or billions of cycles per second)

Timing diagram

x-axis: time

y-axis: voltage

values 0 and 1 are represented by low and high voltage

A clock is a device which alternates values between 0 and 1

period: time T

cycle: single alternation between 0 and 1

frequency: f = 1/T, units of Hz (cycles per second)

1 GHz means 109 cycles per second

(period is 10-9 seconds, which is 1 nanosecond)