Wide-issue
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Wide-issue
A wide-issue architecture is a computer processor that issues more than one instruction per clock cycle. They can be considered in three broad types: * Statically-scheduled superscalar architectures execute instructions in the order presented; the hardware logic determines which instructions are ready and safe to dispatch on each clock cycle. * VLIW architectures rely on the programming software (compiler) to determine which instructions to dispatch on a given clock cycle. * Dynamically-scheduled superscalar architectures execute instructions in an order that gives the same result as the order presented; the hardware logic determines which instructions are ready and safe to dispatch on each clock cycle. See also *Out-of-order execution *Explicitly parallel instruction computing Explicitly parallel instruction computing (EPIC) is a term coined in 1997 by the Itanium, HP–Intel alliance to describe a computing paradigm that researchers had been investigating since the early 19 ...
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VLIW
Very long instruction word (VLIW) refers to instruction set architectures that are designed to exploit instruction-level parallelism (ILP). A VLIW processor allows programs to explicitly specify instructions to execute in parallel computing, parallel, whereas conventional central processing units (CPUs) mostly allow programs to specify instructions to execute in sequence only. VLIW is intended to allow higher performance without the complexity inherent in some other designs. The traditional means to improve performance in processors include dividing instructions into sub steps so the instructions can be executed partly at the same time (termed ''pipelining''), dispatching individual instructions to be executed independently, in different parts of the processor (''superscalar architectures''), and even executing instructions in an order different from the program (''out-of-order execution''). These methods all complicate hardware (larger circuits, higher cost and energy use) becaus ...
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Explicitly Parallel Instruction Computing
Explicitly parallel instruction computing (EPIC) is a term coined in 1997 by the Itanium, HP–Intel alliance to describe a computing paradigm that researchers had been investigating since the early 1980s. This paradigm is also called ''Independence'' architectures. It was the basis for Intel and Hewlett-Packard, HP development of the Intel Itanium architecture, and Hewlett-Packard, HP later asserted that "EPIC" was merely an old term for the Itanium architecture. EPIC permits microprocessors to execute software instructions in parallel by using the compiler, rather than complex on-die (integrated circuit), die circuitry, to control parallel instruction execution. This was intended to allow simple performance scaling without resorting to higher clock rate, clock frequencies. Roots in VLIW By 1989, researchers at HP recognized that reduced instruction set computer (RISC) architectures were reaching a limit at one instruction per cycle. They began an investigation into a new archite ...
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Instruction Per Clock Cycle
Instruction or instructions may refer to: A specific direction or order given to someone to perform a task or carry out a procedure. They provide clear guidance on how to achieve a desired outcome. They can be written or verbal, and they typically include detailed steps or actions to follow. Instructions are crucial for ensuring tasks are completed correctly and efficiently. Computing * Instruction, one operation of a processor within a computer architecture instruction set * Computer program, a collection of instructions Music * Instruction (band), a 2002 rock band from New York City, US * "Instruction" (song), a 2017 song by English DJ Jax Jones * ''Instructions'' (album), a 2001 album by Jermaine Dupri Other uses * Instruction, teaching or education performed by a teacher * Sebayt, a work of the ancient Egyptian didactic literature aiming to teach ethical behaviour * Instruction, the pre-trial phase of an investigation led by a judge in an inquisitorial system of justice * I ...
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Superscalar
A superscalar processor (or multiple-issue processor) is a CPU that implements a form of parallelism called instruction-level parallelism within a single processor. In contrast to a scalar processor, which can execute at most one single instruction per clock cycle, a superscalar processor can execute or start executing more than one instruction during a clock cycle by simultaneously dispatching multiple instructions to different execution units on the processor. It therefore allows more throughput (the number of instructions that can be executed in a unit of time which can even be less than 1) than would otherwise be possible at a given clock rate. Each execution unit is not a separate processor (or a core if the processor is a multi-core processor), but an execution resource within a single CPU such as an arithmetic logic unit. While a superscalar CPU is typically also pipelined, superscalar and pipelining execution are considered different performance enhancement techni ...
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Out-of-order Execution
In computer engineering, out-of-order execution (or more formally dynamic execution) is an instruction scheduling paradigm used in high-performance central processing units to make use of instruction cycles that would otherwise be wasted. In this paradigm, a processor executes instructions in an order governed by the availability of input data and execution units, rather than by their original order in a program. In doing so, the processor can avoid being idle while waiting for the preceding instruction to complete and can, in the meantime, process the next instructions that are able to run immediately and independently. History Out-of-order execution is a restricted form of dataflow architecture, which was a major research area in computer architecture in the 1970s and early 1980s. Early use in supercomputers The first machine to use out-of-order execution was the CDC 6600 (1964), designed by James E. Thornton, which uses a scoreboard to avoid conflicts. It permits ...
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Instruction Processing
Instruction or instructions may refer to: A specific direction or order given to someone to perform a task or carry out a procedure. They provide clear guidance on how to achieve a desired outcome. They can be written or verbal, and they typically include detailed steps or actions to follow. Instructions are crucial for ensuring tasks are completed correctly and efficiently. Computing * Instruction, one operation of a processor within a computer architecture instruction set * Computer program, a collection of instructions Music * Instruction (band), a 2002 rock band from New York City, US * "Instruction" (song), a 2017 song by English DJ Jax Jones * ''Instructions'' (album), a 2001 album by Jermaine Dupri Other uses * Instruction, teaching or education performed by a teacher * Sebayt, a work of the ancient Egyptian didactic literature aiming to teach ethical behaviour * Instruction, the pre-trial phase of an investigation led by a judge in an inquisitorial system of justice * I ...
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