Computer Organization

• All the circuits in the CPU are synchronized by the system clock.
• The clock is an input to all sequential circuits; it changes from 1 to 0 and back again at regular intervals (the clock cycle), and controls when the state of a circuit changes.
• Modern processors typically complete instructions (i.e., fetch-execute cycles) at the rate of 1 per clock cycle. In fact, many use multiple instruction ``pathways'' or ``pipelines'' in an attempt to complete more than one instruction per cycle.
• The clock rate is measured in "MHz" (megahertz), where 1 MHz is 1 million cycles per second.
• Example. A 100 Mhz processor has a clock cycle time of 10 nanoseconds. (Do you see why?)

CS1104 Main Page
Last Updated 2001/10/10
© L.Heath, 2000, extensively modified by J.A.N. Lee, 2001.