Computer Memory Addressing Employing Base and Index Registers.
DEPARTMENT OF THE NAVY WASHINGTON D C
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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.
- Computer Programming and Software
- Computer Hardware