Lexra
Encyclopedia
Lexra was a semiconductor intellectual property core
Semiconductor intellectual property core
In electronic design a semiconductor intellectual property core, IP core, or IP block is a reusable unit of logic, cell, or chip layout design that is the intellectual property of one party. IP cores may be licensed to another party or can be owned and used by a single party alone...

 company based in Waltham, Massachusetts
Waltham, Massachusetts
Waltham is a city in Middlesex County, Massachusetts, United States, was an early center for the labor movement, and major contributor to the American Industrial Revolution. The original home of the Boston Manufacturing Company, the city was a prototype for 19th century industrial city planning,...

. It was founded in 1997 and began developing and licensing semiconductor intellectual property cores that implemented the MIPS-I instruction set, except for the four unaligned load and store (lwl, lwr, swl, swr) instructions.

Lexra did not implement those instructions because they are not necessary for good performance in modern software and Silicon Graphics
Silicon Graphics
Silicon Graphics, Inc. was a manufacturer of high-performance computing solutions, including computer hardware and software, founded in 1981 by Jim Clark...

 owned a patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

 that had originally been granted to MIPS Computer Systems Inc. for implementing unaligned loads and stores in a RISC processor and Lexra did not wish to pay a high license fee for permission to use the patent.

Lexra licensed soft cores unlike ARM Ltd at the time. Lexra was probably the first semiconductor intellectual property core company to do so.

In 1998 Silicon Graphics spun out MIPS Technologies Inc. as a Semiconductor IP licensing company that would compete directly with Lexra. MIPS Technologies sued Lexra claiming a trademark
Trademark
A trademark, trade mark, or trade-mark is a distinctive sign or indicator used by an individual, business organization, or other legal entity to identify that the products or services to consumers with which the trademark appears originate from a unique source, and to distinguish its products or...

 infringement for Lexra's claims of compatibility with the MIPS-I instruction set. Lexra and MIPS Technologies settled the dispute by agreeing that in all public statements Lexra would clearly state that it did not implement unaligned loads and stores.

In 1999 MIPS Technologies
MIPS Technologies
MIPS Technologies, Inc. , formerly MIPS Computer Systems, Inc., is most widely known for developing the MIPS architecture and a series of pioneering RISC chips. MIPS provides processor architectures and cores for digital home, networking and mobile applications.MIPS Computer Systems Inc. was...

 sued Lexra again, but this time for infringing its patents on unaligned loads and stores. Though Lexra's processor designs did not implement unaligned loads and stores, it was possible to emulate the functionality of unaligned loads and stores through a long series of other instructions. In the opinion of Lexra, the ability to emulate the function of unaligned loads and stores in software predated the grant of the patent in question and could not be viewed as an infringement of the hardware patent by any reasonable interpretation. Also, much earlier than any MIPS Technologies
MIPS Technologies
MIPS Technologies, Inc. , formerly MIPS Computer Systems, Inc., is most widely known for developing the MIPS architecture and a series of pioneering RISC chips. MIPS provides processor architectures and cores for digital home, networking and mobile applications.MIPS Computer Systems Inc. was...

 processor, IBM mainframes supported unaligned memory operations. In these earlier IBM processors, unaligned memory operations and partial access to registers were available through microcode and the instruction set architecture. These aspects of earlier IBM processors posed the much greater threat of patent invalidation to MIPS Technologies
MIPS Technologies
MIPS Technologies, Inc. , formerly MIPS Computer Systems, Inc., is most widely known for developing the MIPS architecture and a series of pioneering RISC chips. MIPS provides processor architectures and cores for digital home, networking and mobile applications.MIPS Computer Systems Inc. was...

, compared to the seemingly vacuous MIPS Technologies
MIPS Technologies
MIPS Technologies, Inc. , formerly MIPS Computer Systems, Inc., is most widely known for developing the MIPS architecture and a series of pioneering RISC chips. MIPS provides processor architectures and cores for digital home, networking and mobile applications.MIPS Computer Systems Inc. was...

 infringement claim against Lexra.

The protracted second lawsuit combined with a downturn in semiconductor industry business forced Lexra into a settlement with MIPS Technologies that included MIPS Technologies paying Lexra a large sum of money and granting Lexra a license to its technologies in exchange for Lexra exiting the IP business.

Lexra failed as a networking / communications fabless semiconductor chip company
Fabless semiconductor company
A fabless semiconductor company specializes in the design and sale of hardware devices and semiconductor chips while outsourcing the fabrication or "fab" of the devices to a specialized manufacturer called a semiconductor foundry...

 and ceased operations in January 2003.

In its 5.5 years, Lexra implemented ten processor designs and licensed nine of them as IP cores. Lexra had the first
  • Synthesizable (RTL to gates) MIPS processor core allowing customer owned tools and customer chosen foundary.
  • IP core to support EJTAG on-chip debug;
  • IP core to support MIPS16 code compression;
  • RISC processor IP core with a 6-stage pipeline; and later the first with a 7-stage pipeline;
  • dual-issue superscalar
    Superscalar
    A superscalar CPU architecture implements a form of parallelism called instruction level parallelism within a single processor. It therefore allows faster CPU throughput than would otherwise be possible at a given clock rate...

     processor IP core;
  • coarse-grained multithreaded processor IP core and later the first fine-grained multithreaded processor IP core


Lexra also enhanced the MIPS-I instruction set with extensions that greatly enhanced performance for digital signal processing
Digital signal processing
Digital signal processing is concerned with the representation of discrete time signals by a sequence of numbers or symbols and the processing of these signals. Digital signal processing and analog signal processing are subfields of signal processing...

(DSP) algorithms.

Sources

  • A more detailed history of Lexra can be found at the web page of former Lexra employee Jonah Probell
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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