Bull Hn Information Systems, Inc.

Ming-Tzer Miu

Jian-Kuo Shen

David E Cushing

Deborah K Staplin

Romeo Kharileh

A pipelined processing unit includes an instruction unit stage containing resource conflict apparatus for detecting and resolving conflicts in the use of register and indicator resources during the different phases of instruction execution. The instruction unit includes a plurality of resource registers corresponding in number to the number of instructions which can be processed concurrently by the processing unit. Decode circuits in response to each new instruction received by the instruction unit generate one or more sets of bit indication signals designating those resources required by the specific pipeline stage(s) executing the instruction for completing the execution of the instruction which are shared by those stages capable of completing the execution of instructions. Comparison circuits compare the set of bit indication signals for each new instruction that corresponds to resources needed by an earlier pipeline stage which in the preferred embodiment corresponds to a secondary execution unit, with the stored sets of bit indication signals for determining the presence of any resource conflict.

Resource conflict detection method and apparatus included in a pipelined

A dual port read/write register file memory includes means for performing a read/modify write cycle of operation within a single system cycle of operation. The register file memory is constructed from one to more (RAM) addressable multibit storage arrays organized to form a dual read port, single write port RAM. Additionally, the register file includes a plurality of clocked input registers arranged in pairs for storing command, address and data signals for two write ports. The different pairs of registers are connected as inputs to a first set of multiplexer circuits whose outputs connect to the write control signal, address and data inputs of the single write port. The single write port of the register file memory is enabled for writing twice during each cycle. This allows data clocked into the input registers during the previous cycle to be written sequentially into the register file storage locations. By writing data into the input registers instead of the register file memory in a previous cycle, the time required for writing is reduced to a minimum.

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Chelmsford, MA, United States of America

Ming-Tzer Miu