Figure 1 illustrates the state transitions between Stop Clock and Auto Halt Powerdown states. The SMI handlers are special software routines that perform various system management functions including system power control. The processor is the most active component in a system. Therefore, clock control in SMM mode allows saving a lot of processor power. As technology advances and faster processor operation is required, efficient power management techniques become crucial for meeting low-power high speed computing demands.
Power management has to be done at both the system level and the processor level.
The Intel486 embedded processor implements aggressive techniques for achieving this goal. The operating system and system hardware are provided with hooks to allow them to control the power activity of the processor. In addition, the auto clock freeze feature allows significant power savings without significant degradation to the processor performance.