Information about Instruction (computer Science)
For other uses, see Instruction.
In computer science, an instruction is a single operation of a processor defined by an instruction set architecture. In a broader sense, an "instruction" may be any representation of an element of an executable program, such as a bytecode.
On traditional architectures, an instruction includes an opcode specifying the operation to be performed, such as "add contents of memory to register", and zero or more operand specifiers, which may specify registers, memory locations, or literal data. The operand specifiers may have addressing modes determining their meaning or may be in fixed fields.
In very long instruction word (VLIW) architectures, which include many microcode architectures, multiple simultaneous operations and operands are specified in a single instruction.
The size or length of an instruction varies widely, from as little as four bits in some microcontrollers to many hundreds of bits in some VLIW systems. Most modern processors used in personal computers, mainframes, and supercomputers have instruction sizes between 16 and 64 bits. In some architectures, notably most Reduced Instruction Set Computers, instructions are a fixed length, typically corresponding with that architecture's word size. In other architectures, instructions have variable length, typically integral multiples of a byte or a halfword.
The instructions constituting a program are rarely specified using their internal, numeric form; they may be specified by programmers using an assembly language or, more commonly, may be generated by compilers.
See also
An instruction is a form of communicated information that is both command and explanation'' for how an action, behavior, method, or task is to be begun, completed, conducted, or executed.
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Computer science, or computing science, is the study of the theoretical foundations of information and computation and their implementation and application in computer systems.
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central processing unit (CPU), or sometimes simply processor, is the component in a digital computer capable of executing a program.(Knott 1974) It interprets computer program instructions and processes data.
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instruction set is (a list of) all instructions, and all their variations, that a processor can execute.
Instructions include:
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Instructions include:
- arithmetic such as add and subtract
- logic instructions such as and, or, and not
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Bytecode is a binary representation of an executable program designed to be executed by a virtual machine rather than by dedicated hardware. Since it is processed by software, it is usually more abstract than machine code.
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In computer science, an opcode (Operation Code) is the portion of a machine language instruction that specifies the operation to be performed. Their specification and format will be laid out in the instruction set architecture (ISA) of the computer hardware component
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In computer architecture, a processor register is a small amount of storage available on the CPU whose contents can be accessed more quickly than storage available elsewhere.
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Addressing modes, a concept from computer science, are an aspect of the instruction set architecture in most central processing unit (CPU) designs. The various addressing modes that are defined in a given instruction set architecture define how machine language instructions in that
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Very Long Instruction Word or VLIW refers to a CPU architecture designed to take advantage of instruction level parallelism (ILP). A processor that executes every instruction one after the other (i.e.
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A microprogram implements a CPU instruction set. Just as a single high level language statement is compiled to a series of machine instructions (load, store, shift, etc), in a CPU using microcode, each machine instruction is in turn implemented by a series of microinstructions,
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microcontroller (or MCU) is a computer-on-a-chip. It is a type of microprocessor emphasizing self-sufficiency and cost-effectiveness, in contrast to a general-purpose microprocessor (the kind used in a PC).
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personal computer (PC) is a computer whose original sales price, size, and capabilities make it useful for individuals.
It is unknown who coined the phrase with the intent of a small affordable computing device but John W.
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It is unknown who coined the phrase with the intent of a small affordable computing device but John W.
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Mainframe may refer to one of the following:
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- Mainframe computer, large data processing systems
- Mainframe Entertainment, a Canadian computer animation and design company.
- Mainframe is the city that the CGI cartoon ReBoot takes place in.
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For other uses, see Supercomputer (disambiguation).
A supercomputer is a computer that led the world (or was close to doing so) in terms of processing capacity, particularly speed of calculation, at the time of its introduction...... Click the link for more information.
reduced instruction set computer (RISC, pronounced like "risk") is a CPU design philosophy that favors an instruction set reduced both in size and complexity of addressing modes, in order to enable easier implementation, greater instruction level parallelism, and
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word" is a term for the natural unit of data used by a particular computer design. A word is simply a fixed-sized group of bits that are handled together by the machine. The number of bits in a word (the word size or word length
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byte (pronounced /baɪt/) is a unit of measurement of information storage, most often consisting of eight bits. In many computer architectures it is a unit of memory addressing.
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In computer science, the term integer is used to refer to any data type which represents some subset of the mathematical integers. These are also known as integral data types.
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assembly language is a low-level language for programming computers. It implements a symbolic representation of the numeric machine codes and other constants needed to program a particular CPU architecture.
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compiler is a computer program (or set of programs) that translates text written in a computer language (the source language) into another computer language (the target language).
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In computing, a command is a directive to a computer program acting as an interpreter of some kind, in order to perform a specific task. Most commonly a command is a directive to some kind of command line interface, such as a shell.
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In computer science, data is any information in a form suitable for use with a computer[1]. Data is often distinguished from programs. A program is a set of instructions that detail a task for the computer to perform.
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Machine code or machine language is a system of instructions and data directly executed by a computer's central processing unit. Machine code is the lowest-level of abstraction for representing a computer program.
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