A system for reducing power consumption in processing apparatus including a memory comprises a clock controller for controlling the clock period of the processing apparatus to switch the processing apparatus to a slow operating mode wherein the clock period is longer then the time required to recover from memory standby mode plus the time to execute a read command in the memory. A memory management module is provided configured for controlling the status of the memory during the slow operating mode by: maintaining the in a stand-by mode when no memory read/write commands are to be executed, and if any said read/write commands are required to be executed, switching said memory on only for the time required to perform the memory read/write commands.