Abstract: A computer system includes a hard disk drive, a processor coupled to the hard disk drive, and a cache interface coupled to the processor and detachably connectable to a cache memory. The processor is adapted, subsequent to an initial interrogation of the cache interface, to determine whether the cache memory is connected to the cache interface by inspecting an indication of the presence or the absence of the cache memory, the indication being stored in a register in the processor or in a memory associated with the processor such that the inspecting avoids repeat interrogation of the cache interface, to communicate with the cache memory and the hard disk drive such that the processor has access to the cache memory when the cache memory is connected to the cache interface, and to communicate with the hard disk drive when the cache memory is disconnected from the cache interface.