Accession Number : ADD002818

Title :   Computer Memory Addressing Employing Base and Index Registers.

Descriptive Note : Patent,


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
      Computer Hardware

Distribution Statement : APPROVED FOR PUBLIC RELEASE