Computer memory address control apparatus utilizing hashed address tags in page tables which are compared to a combined address tag and index which are longer than the basic data width of the associated computer

摘要

The present invention relates to the design of computer systems incorporating virtual memory where a virtual page number is longer than the inherent basic data width of the designed computer system. Instead of storing an entire tag in page table entries, a reduced tag is stored. The reduced tag is sized to be no greater in length than the basic computer data width and therefore a single compare operation will ascertain whether there is a match between the reduced tag and the tag stored in a page table entry. To maintain uniqueness of the page table entries, any bits removed from the virtual address to form the reduced tag are used to form an index into the page table.