Computer operand address computation
AssigneeMicrodata Corporation
InventorsRichard Vahlstrom, Dennis R. Keats
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Abstract
The address of an operand in computer main memory is computed by a system which utilizes a base memory frame address in combination with a displacement value, indicative of the position in the frame of the operand relative to the base memory frame address, and information relating to the length of the operand to supply system hardware with the necessary information to enable a fetch of the operand from main memory. This system has the capability to compute addresses for multi-byte word operands within a single firmware clock cycle.
Claims5
An address computation (ADC) system for use in a computer system for determining an absolute main memory address of an operand stored in main memory wherein the initial address of the operand is defined in terms of a base address, a displacement from the base address and a constant comprising:
- initial address input means to supply the ADC with the initial address originating from a direct software instruction from the computer system arithmetic logic unit (ALU) and a firmware word latched onto an instruction register in the ALU;
- address register means for storing the base address of the operand;
- displacement register means for storing the initial displacement for the operand received from the firmware word;
- adder means for combining the constant received from the firmware word and the displacement with the base address to produce the absolute main memory address;
- and
- output means to supply the absolute main memory address to memory address bus means in the computer system via at least one of two separate, selectable hardware address registers.
Dependencies are inferred from the claim text.