9. The invention in accordance with claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein said selectively addressable memory is an associative memory which is automatically searched in response to data incorporated in an S memory address requesting access to said S memory for corresponding S memory access rights data indicating whether the requested S memory access is to be permitted.
9. The invention in accordance with claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein said selectively addressable memory is an associative memory which is automatically searched in response to data incorporated in an S memory address requesting access to said S memory for corresponding S memory access rights data indicating whether the requested S memory access is to be permitted. 10. The invention in accordance with claim 9, wherein said associative memory stores a plurality of S memory access descriptors each of which comprises a key and S memory access rights data applicable to particular data stored in said S memory, and wherein S memory addresses each include a corresponding key which is used in associatively searching said associative memory to select a corresponding S memory access descriptor to determine applicable access rights prior to permitting access to said S memory.