Data storage unit employing translation lookaside buffer pointer

Abstract

A data processing system includes virtual-addressed and real-addressed stores. Whenever an addressed location is not resident in the memory in which it is attempted to be accessed, the address is translated to the other address space. If a virtual address cannot access the desired location in the virtual memory the virtual address through a virtual-to-real translator is translated to a real address and the location is addressed in the real memory. Whenever a real address needs to access a virtual address in the virtual-addressed memory, the real address is converted through a real-to-virtual translator in order to locate corresponding locations in the virtual-addressed memory. Virtual-to-real translation is carried out by storing the real addresses corresponding to a virtual address in a translation lookaside buffer. Entry to the translation lookaside buffer is gained by using a TLB pointer in a tag array which points to the TLB address which contains the desired real address. By storing a TLB pointer in the tag array rather than storing the full address, many bits are saved in the tag array.