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Register Renaming
In computer architecture, register renaming is a technique that abstracts logical registers from physical registers. Every logical register has a set of physical registers associated with it. When a machine language instruction refers to a particular logical register, the processor transposes this name to one specific physical register on the fly. The physical registers are opaque and cannot be referenced directly but only via the canonical names. This technique is used to eliminate false data dependencies arising from the reuse of registers by successive instructions that do not have any real data dependencies between them. The elimination of these false data dependencies reveals more instruction-level parallelism in an instruction stream, which can be exploited by various and complementary techniques such as superscalar and out-of-order execution for better performance. Problem approach In a register machine, programs are composed of instructions which operate on values. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Architecture
In computer engineering, computer architecture is a description of the structure of a computer system made from component parts. It can sometimes be a high-level description that ignores details of the implementation. At a more detailed level, the description may include the instruction set architecture design, microarchitecture design, logic design, and implementation. History The first documented computer architecture was in the correspondence between Charles Babbage and Ada Lovelace, describing the analytical engine. When building the computer Z1 in 1936, Konrad Zuse described in two patent applications for his future projects that machine instructions could be stored in the same storage used for data, i.e., the stored-program concept. Two other early and important examples are: * John von Neumann's 1945 paper, First Draft of a Report on the EDVAC, which described an organization of logical elements; and *Alan Turing's more detailed ''Proposed Electronic Calculator'' for t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loop Unrolling
Loop unrolling, also known as loop unwinding, is a loop transformation technique that attempts to optimize a program's execution speed at the expense of its binary size, which is an approach known as space–time tradeoff. The transformation can be undertaken manually by the programmer or by an optimizing compiler. On modern processors, loop unrolling is often counterproductive, as the increased code size can cause more cache misses; ''cf.'' Duff's device. The goal of loop unwinding is to increase a program's speed by reducing or eliminating instructions that control the loop, such as pointer arithmetic and "end of loop" tests on each iteration; reducing branch penalties; as well as hiding latencies, including the delay in reading data from memory. To eliminate this computational overhead, loops can be re-written as a repeated sequence of similar independent statements. Loop unrolling is also part of certain formal verification techniques, in particular bounded model checkin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM System/360 Model 91
The IBM System/360 Model 91 was announced in 1964 as a competitor to the CDC 6600. Functionally, the Model 91 ran like any other large-scale System/360, but the internal organization was the most advanced of the System/360 line, and it was the first IBM computer to support out-of-order instruction execution. It ran OS/360 as its operating system. It was designed to handle high-speed data processing for scientific applications. This included space exploration, theoretical astronomy, sub-atomic physics and global weather forecasting. The first Model 91 was used at the NASA Goddard Space Flight Center in 1968 and at the time was the most powerful computer in user operation. It was capable of executing up to 16.6 million instructions per second, making it roughly equivalent to an intel 80486SX-20 MHz CPU or AMD 80386DX-40 MHz CPU in MIPS performance. The CPU consisted of five autonomous units: instruction, floating-point, fixed-point, and two storage controllers for the overla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Re-order Buffer
A re-order buffer (ROB) is a hardware unit used in an extension to the Tomasulo algorithm to support out-of-order and speculative instruction execution. The extension forces instructions to be committed in-order. The buffer is a circular buffer (to provide a FIFO instruction ordering queue) implemented as an array/vector (which allows recording of results against instructions as they complete out of order). There are three stages to the Tomasulo algorithm: "Issue", "Execute", "Write Result". In an extension to the algorithm, there is an additional "Commit" stage. During the Commit stage, instruction results are stored in a register or memory. The "Write Result" stage is modified to place results in the re-order buffer. Each instruction is tagged in the reservation station A unified reservation station, also known as unified scheduler, is a decentralized feature of the microarchitecture of a CPU that allows for register renaming In computer architecture, register renami ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Register Renaming:reservation Station Scheme
Register or registration may refer to: Arts entertainment, and media Music * Register (music), the relative "height" or range of a note, melody, part, instrument, etc. * ''Register'', a 2017 album by Travis Miller * Registration (organ), the art of combining the different sounds of a pipe organ to produce the desired sound Periodicals Australia * '' South Australian Register'', later ''The Register'', originally the ''South Australian Gazette and Colonial Register'' United Kingdom * '' Sheffield Register'', England * ''Socialist Register'', an annual British journal * ''The Register'', a technology news website United States * '' Federal Register'', a public journal of the United States federal government * ''Napa Valley Register'', Napa Valley, California * ''National Catholic Register'', the oldest national Catholic newspaper in the United States * ''New Haven Register'', Connecticut * '' Orange County Register'', Santa Ana, California * ''Social Register'', one of a n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reorder Buffer
A re-order buffer (ROB) is a hardware unit used in an extension to the Tomasulo algorithm to support out-of-order and speculative instruction execution. The extension forces instructions to be committed in-order. The buffer is a circular buffer (to provide a FIFO instruction ordering queue) implemented as an array/vector (which allows recording of results against instructions as they complete out of order). There are three stages to the Tomasulo algorithm: "Issue", "Execute", "Write Result". In an extension to the algorithm, there is an additional "Commit" stage. During the Commit stage, instruction results are stored in a register or memory. The "Write Result" stage is modified to place results in the re-order buffer. Each instruction is tagged in the reservation station with its index in the ROB for this purpose. The contents of the buffer are used for data dependencies of other instructions scheduled in the buffer. The head of the buffer will be committed once its result is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Athlon
Athlon is the brand name applied to a series of x86-compatible microprocessors designed and manufactured by Advanced Micro Devices (AMD). The original Athlon (now called Athlon Classic) was the first seventh-generation x86 processor and the first desktop processor to reach speeds of one gigahertz (GHz). It made its debut as AMD's high-end processor brand on June 23, 1999. Over the years AMD has used the Athlon name with the 64-bit Athlon 64 architecture, the Athlon II, and Accelerated Processing Unit (APU) chips targeting the Socket AM1 desktop SoC architecture, and Socket AM4 Zen microarchitecture. The modern Zen-based Athlon with a Radeon Graphics processor was introduced in 2019 as AMD's highest-performance entry-level processor. Athlon comes from the Ancient Greek (''athlon''), meaning "(sport) contest", or "prize of a contest", or "place of a contest; arena". With the Athlon name originally used for AMD's high-end processors, AMD currently uses Athlon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
R10000
The R10000, code-named "T5", is a RISC microprocessor implementation of the MIPS IV instruction set architecture (ISA) developed by MIPS Technologies, Inc. (MTI), then a division of Silicon Graphics, Inc. (SGI). The chief designers are Chris Rowen and Kenneth C. Yeager. The R10000 microarchitecture is known as ANDES, an abbreviation for Architecture with Non-sequential Dynamic Execution Scheduling. The R10000 largely replaces the R8000 in the high-end and the R4400 elsewhere. MTI was a fabless semiconductor company; the R10000 was fabricated by NEC and Toshiba. Previous fabricators of MIPS microprocessors such as Integrated Device Technology (IDT) and three others did not fabricate the R10000 as it was more expensive to do so than the R4000 and R4400. History The R10000 was introduced in January 1996 at clock frequencies of 175 MHz and 195 MHz. A 150 MHz version was introduced in the O2 product line in 1997, but discontinued shortly after due to customer prefer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Register Renaming:tag Indexed Scheme
Register or registration may refer to: Arts entertainment, and media Music * Register (music), the relative "height" or range of a note, melody, part, instrument, etc. * ''Register'', a 2017 album by Travis Miller * Registration (organ), the art of combining the different sounds of a pipe organ to produce the desired sound Periodicals Australia * '' South Australian Register'', later ''The Register'', originally the ''South Australian Gazette and Colonial Register'' United Kingdom * '' Sheffield Register'', England * ''Socialist Register'', an annual British journal * ''The Register'', a technology news website United States * '' Federal Register'', a public journal of the United States federal government * ''Napa Valley Register'', Napa Valley, California * ''National Catholic Register'', the oldest national Catholic newspaper in the United States * ''New Haven Register'', Connecticut * '' Orange County Register'', Santa Ana, California * ''Social Register'', one of a n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keith Diefendorff
Keith Diefendorff is a computer architect and veteran in the microprocessor industry. Diefendorff is one of the persons that has led the industry in developing RISC processors, both for embedded systems and superscalar high performance systems. He is one of the main designers of the PowerPC family of processors. Background Keith Diefendorff started at Texas Instruments, designing integrated circuits processors and systems. Later Diefendorff joined Motorola and was the chief architect of a second-generation implementation of the 88000 instruction set architecture, the 88110. The 88110 was not a commercial success, and when Motorola shifted focus to creating a new RISC architecture with IBM, Diefendorff was assigned as chief architect for the PowerPC. After his work at Motorola Diefendorrf moved to NexGen as director of technical x86-strategy. Diefendorff joined AMD when NexGen was acquired by AMD. From AMD Diefendorrf then moved to Apple as architect for the AltiVec med ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Content-addressable Memory
Content-addressable memory (CAM) is a special type of computer memory used in certain very-high-speed searching applications. It is also known as associative memory or associative storage and compares input search data against a table of stored data, and returns the address of matching data. CAM is frequently used in networking devices where it speeds up forwarding information base and routing table operations. This kind of associative memory is also used in cache memory. In associative cache memory, both address and content is stored side by side. When the address matches, the corresponding content is fetched from cache memory. History Dudley Allen Buck invented the concept of content-addressable memory in 1955. Buck is credited with the idea of ''recognition unit''. Hardware associative array Unlike standard computer memory, random-access memory (RAM), in which the user supplies a memory address and the RAM returns the data word stored at that address, a CAM is designed suc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha 21264
The Alpha 21264 is a Digital Equipment Corporation RISC microprocessor launched on 19 October 1998. The 21264 implemented the Alpha instruction set architecture (ISA). Description The Alpha 21264 is a four-issue superscalar microprocessor with out-of-order execution and speculative execution. It has a peak execution rate of six instructions per cycle and could sustain four instructions per cycle. It has a seven-stage instruction pipeline. Out of order execution At any given stage, the microprocessor could have up to 80 instructions in various stages of execution, surpassing any other contemporary microprocessor. Decoded instructions are held in instruction queues and are issued when their operands are available. The integer queue contained 20 entries and the floating-point queue 15. Each queue could issue as many instructions as there were pipelines. Ebox The Ebox executes integer, load and store instructions. It has two integer units, two load store units and two integer r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
