1. A method of operating a cache memory arranged between a processor and a main memory of a computer, the processor being capable of executing a plurality of processes wherein each process includes a sequence of instructions, the method comprising: dividing the cache memory into cache partitions, each cache partition having a plurality of addressable storage locations for holding items in the cache memory; allocating to each process a partition indicator identifying which, if any, of said cache partitions is to be used for holding items for use in the execution of that process; and when the processor requests an item from main memory during execution of said current process and that item is not held in the cache memory, fetching the item from main memory and loading it into one of the plurality of addressable storage locations in the identified cache partition.