1. In a data processing system comprising a plurality of local and remote type memories, a system interface unit which includes a plurality of local memory ports and a plurality of remote memory ports, said memory ports connected to said local and said remote memories respectively, and an input/output processor, the method of controlling data fetches employing a three part memory address comprised of: a. generating in said input/output processor a first address portion indicating the type of memory to be accessed; b. generating in said input/output processor a second address portion indicating which memory is to be accessed; c. generating in said input/output processor a third address portion to verify the memory address is indicating the correct page table word and page number; and d. obtaining by means of said interface unit the correct page table word and page number from remote memory if step c. does not verify that the correct page table word and page number was indicated.