Microprocessor having software controllable power consumption

Abstract

A microprocessor is provided which includes a power control register for controlling the rate of execution and therefore the power consumption of individual functional units. The power control register includes a plurality of fields corresponding to the functional units for storing values that control the power consumption of each. The power control register fields can be set by software which has the much greater ability to look out into the future to determine whether the functional units will be required. The functional units are responsive to the corresponding power control register field to adjust their rate of execution responsive to the value stored therein. The rate of execution can be controlled in a number of different ways: dividing down the clock; removing power to the functional unit; disabling the sensor and/or buffer driver of one or more of the ports in a multi-ported RAM; removing data from the functional unit; and changing the data bus width responsive to the control register field. The microprocessor also includes a latency control register which assures that the functional unit is operational after the functional unit is placed from a low power state to a more fully operational state by changing the corresponding field in the power control register.