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In computer science, an instruction set architecture (ISA) is an abstract model that generally defines how software controls the CPU in a computer or a family of computers. [1] A device or program that executes instructions described by that ISA, such as a central processing unit (CPU), is called an implementation of that ISA.
The XSAVE instruction set extensions are designed to save/restore CPU extended state (typically for the purpose of context switching) in a manner that can be extended to cover new instruction set extensions without the OS context-switching code needing to understand the specifics of the new extensions.
Some instruction sets have nearly uniform fields for opcode and operand specifiers, whereas others (e.g., x86 architecture) have a less uniform, variable-length structure. [ 10 ] [ 11 ] Instruction sets can be extended through the use of opcode prefixes which add a subset of new instructions made up of existing opcodes following reserved byte ...
While the integer ability is often overlooked, the x87 can operate on larger integers with a single instruction than the 8086, 80286, 80386, or any x86 CPU without to 64-bit extensions can, and repeated integer calculations even on small values (e.g., 16-bit) can be accelerated by executing integer instructions on the x86 CPU and the x87 in ...
The SHARE Operating System (1959) for the IBM 709, IBM 7090, and IBM 7094 computers allowed for an loadable code format named SQUOZE. SQUOZE was a compressed binary form of assembly language code and included a symbol table. Modern IBM mainframe operating systems, such as z/OS, have available a symbol table named Associated data (ADATA).
Operating systems ported to the architecture include SGI's IRIX, Microsoft's Windows NT (through v4.0), Windows CE, Linux, FreeBSD, NetBSD, OpenBSD, UNIX System V, SINIX, QNX, and MIPS Computer Systems' own RISC/os. In the early 1990s, speculation occurred that MIPS and other powerful RISC processors would overtake the Intel IA-32 architecture.
An instruction set architecture (ISA) is an abstract model of a computer, also referred to as computer architecture.A realization of an ISA is called an implementation.An ISA permits multiple implementations that may vary in performance, physical size, and monetary cost (among other things); because the ISA serves as the interface between software and hardware.
In computing, the instruction register (IR) or current instruction register (CIR) is the part of a CPU's control unit that holds the instruction currently being executed or decoded. [1] In simple processors, each instruction to be executed is loaded into the instruction register, which holds it while it is decoded, prepared and ultimately ...