less than the threshold 415 the fullness monitor 410 provides an indicator through output registers 430 that the level of activity is low the power module can use the reported level of activity to initiate a reduced operation mode in which power to some components is disabled furthermore slower clocks signals can be used to conserve power a rate of change monitor 420 is used to monitor a rate of change in the number of pending instructions in the instruction buffer the rate of change monitor 420 may calculate the rate of change in the number of pending instructions tracked through fullness monitor 410 if the number of pending instructions increases at a high rate the rate of change monitor 420 may provide a warning of increased activity to the power module through output registers 430 the power module may use the warning to switch from a reduced operations mode to a normal mode accordingly the rate of change monitor 420 allows the power module to anticipate and react to the changes in the level of activity in one embodiment the fullness monitor 410 and rate of change monitor 420 include discrete components for monitoring the instruction buffer for example fullness monitor may include logic circuitry to toggle a flag on output registers 430 to indicate a particular power mode when a memory address being written to matches threshold 415 in one embodiment instruction monitoring module 400 forms a part of a hardware subsystem to process display instructions associated with a pda instruction monitoring.