05560035 is referenced by 72 patents and cites 10 patents.

A register system for a data processor which operates in a plurality of modes. The register system provides multiple, identical banks of register sets, the data processor controlling access such that instructions and processes need not specify any given bank. An integer register set includes first (RA[23:0]) and second (RA[31:24]) subsets, and a shadow subset (RT[31:24]). While the data processor is in a first mode, instructions access the first and second subsets. While the data processor is in a second mode, instructions may access the first subset, but any attempts to access the second subset are re-routed to the shadow subset instead, transparently to the instructions, allowing system routines to seemingly use the second subset without having to save and restore data which user routines have written to the second subset. A re-typable register set provides integer width data and floating point width data in response to integer instructions and floating point instructions, respectively. Boolean comparison instructions specify particular integer or floating point registers for source data to be compared, and specify a particular Boolean register for the result, so there are no dedicated, fixed-location status flags. Boolean combinational instructions combine specified Boolean registers, for performing complex Boolean comparisons without intervening conditional branch instructions, to minimize pipeline disruption.

Title
RISC microprocessor architecture implementing multiple typed register sets
Application Number
726773
Publication Number
5560035
Application Date
June 5, 1995
Publication Date
September 24, 1996
Inventor
Sho L Chen
Saratoga
CA, US
Le T Nguyen
Monte Sereno
CA, US
Derek J Lentz
Los Gatos
CA, US
Sanjiv Garg
Fremont
CA, US
Agent
Sterne Kessler Goldstein & Fox P L L C
Assignee
Seiko Epson Corporation
JP
IPC
G06F 9/34
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