The present invention provides a mechanism of storing data transferred from an I/O device, a network, or a disk into a portion of a cache or other fast memory, without also writing it to main memory. Further, the data is “locked” into the cache or other fast memory until it is loaded for use. Data remains in the locking cache until it is specifically overwritten under software control. In an embodiment of the invention, a processor can write data to the cache or other fast memory without also writing it to main memory. The portion of the cache or other fast memory can be used as additional system memory.