Unisys Corporation

Steven H Leibowitz

Gary C Wu

Chandra S Pawar

Edward J Pullin

Joseph C Duggan

Michael J Hazzard

A microprocessor architecture that includes an arithmetic logic unit (ALU), a bit processing unit (BPU), a register file and an instruction register is disclosed. The BPU performs complex logical operations in a single clock cycle. The ALU continues to perform the slow arithmetic operations (e.g., multiply, divide). The BPU has two special purpose registers, a zero flag and a match flag, which are used for program execution control. The BPU performs bit manipulations on data stored in and received from the register file and/or individual fields in the instruction currently being executed by the BPU.

Bit processing unit for performing complex logical operations within a

Disclosed is a Significant Bit Calculator (SBC) for determining the number of significant bits or nibbles of an operand in one clock period, and for using the result in performing binary arithmetic operations, such as multiplication and division. By determining the exact size of the operand in one clock cycle, the time spent on processing leading zeros is eliminated. The SBC can be implemented with combinational logic circuitry to compute the number of significant bits or nibbles in a single clock cycle regardless of the number of leading zeros and without any firmware or counter. The time saved using the SBC is proportional to the size of the operand.

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Norristown, PA, United States of America

Steven H Leibowitz