Abstract: A cache interface circuit includes a processor interface for receiving memory access requests from a processor, and for transmitting memory data back to the processor in response to processor requests. A main memory interface provides for issuing main memory access requests to a main memory and for receiving main memory data in response. A cache memory interface provides for issuing memory access requests to a cache memory, if operating in a cache mode, and for receiving cache memory data in response. A cache-bypass mode-control signal input provides for the processor to indicate a cache-bypass mode in which memory access requests are serviced from the main memory. A power control output provides for switching off operating power to the cache memory in response to a command received at the cache-bypass mode-control signal input that indicates all memory access requests should be serviced from the main memory.

Abstract: In a reduced power mode a first data processing unit forming part of a data processing system offers a second data processing unit access to its associated memory in order to optimize the use of energy and available resources. The first data processing unit requires reduced storage space in the reduced power mode, which remaining storage space can be made available to the second data processing unit. The memory associated to the second data processing unit can be switched off to save energy, or can be removed altogether if the second data processing unit only operates in the reduced power mode.

Abstract: A data processing circuit is switchable between operation in a cache mode and a cache bypass mode. In the cache bypass mode the power supply to a cache memory is switched off to reduce power consumption.