Unisys Corporation

Arthur J Nilson

Michael J Saunders

Steven M O'Brien

Robert A Johnson

Mitchell A Bauman

Douglas E Morrissey

Steven T Hurlock

Jayant S Pandya

Stephen Kun

Jeremy S Nichols

Code coverage questions are addressed by a code coverage method that instruments an electronic module source design file with coverage probes and gives hierarchical names to the probes, then provides therefrom an instrumented gate level netlist. The instrumented netlist is run on a hardware emulator, executing reset trigger scripts to reset the branch and statement probes, and then a fully initialized design is driven in emulation on a simulated testbench from which the probe values are retrieved. These values can then be evaluated to determine the extent of code coverage. Various forms of coverage are supported including branch, statement, reset trigger and toggle coverage.

Code coverage testing in hardware emulation

A system and method for enabling a multiprocessor system employing a memory hierarchy to identify data units or locations being used as software locks. The memory hierarchy comprises a main memory having a plurality of data units, a plurality of caches that operate independently of each other, and at least one coherent domain interfaced to each cache. Each coherent domain comprises at least two processors. The main memory maintains coherency of data among the plurality of caches using a directory that maintains information about each data line. The system of the present invention allows a requesting agent, such as a processor or cache, to request a data unit without specifying the type of ownership, where ownership may be exclusive or shared. The directory includes history information that defines the previous access pattern of the requested data unit. Prior to forwarding the requested data unit to the requesting agent, the main memory checks, using a conditional fetch command, the history information to determine what type of ownership to associate with the requested data unit. The requested data unit is then delivered to the requesting agent with ownership rights specified by the history information. The processors may utilize a directory-based protocol such as MESI (modified, exclusive, shared, invalid) to maintain coherence among the processors, with each processor snooping a shared bus to track the status of caches lines in the other processors.

Computer system including plural caches and utilizing access history or

A mainframe computing system is adapted to be loaded with one of a plurality of different operating systems and different associated microcode to provide a computing system which is capable of running user programs adapted to be executed by the loaded operated system comprises a main memory for receiving the desired operating system coupled to a system bus. An instruction processor and an input/output control processor are coupled to the system bus and are provided with an instruction register for presenting user program instructions to the processors. The processor means have associated therewith microcode storage memory which receive and store a set of microcode instructions to be performed by the processors according to the program instruction stored in the instruction register. The stored microcode comprises primary microcode instructions to carry out each of the instructions in the instruction register means. No compiling or emulation is necessary to provide a software configurable computing system adapted to run user programs according to one of a plurality of operating systems loadable in the main memory.

Dual operating system computer

An apparatus for enhancing the operation of a M byte instruction word CPU when operating user programs on an N byte instruction word CPU. The M-Byte instruction word CPU is provided with an N-Byte instruction register and a main memory for supplying N-Byte instruction words or M-Byte instruction words to said N-Byte instruction register. An operational code multiplexer and an parameter code multiplexer are connectable to selective outputs of said instruction register so that any one of the M-Bytes may be selected as an operational code and any one of the remaining M-Bytes may be selected as parameter code bytes, and selection means including sequencer means are provided for operating the operational code multiplexer and the parameter code multiplexer in an M-Byte instruction word CPU mode of operation or as an N-Byte instruction word CPU mode of operation.

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Phoenixville, PA, United States of America

Arthur J Nilson