Accession Number : ADD002818
Title : Computer Memory Addressing Employing Base and Index Registers.
Descriptive Note : Patent,
Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON D C
Personal Author(s) : Crabb,Robert P ; Unger,Robert A ; Gilbreath,Jim A
Report Date : 06 Apr 1976
Pagination or Media Count : 7
Abstract : The patent describes a memory addressing system which enables a computer to address a total of 1,048,575 words (32 times its original capacity) with minimal impact upon existing software. The method employed by this invention involves a new dual usage of the b (index) designator in each instruction word so that in addition to its normal function of specifying which of 8 index registers is to be added to the address portion of the instruction, it also specifies which of 8 base registers is to be arithmetically added to the basic 15-bit address to determine the final 20-bit absolute memory location address. A total of 262,144 words may be accessed by this dual use of the b designator for any one setting of the base registers. Each program module is designed to operate in a 32,768 word environment and no coding changes need be made to it; the computer operator need only maintain the appropriate offset values in the base registers for the module currently in operation.
Descriptors : *Data storage systems, *Computer programming, *Addressing, *Patents, Memory devices, Naval equipment, Shipboard, Registers(Circuits)
Subject Categories : Computer Programming and Software
Distribution Statement : APPROVED FOR PUBLIC RELEASE