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In the x86 computer architecture, HLT (halt) is an assembly language instruction which halts the central processing unit (CPU) until the next external interrupt is fired. [1] Interrupts are signals sent by hardware devices to the CPU alerting it that an event occurred to which it should react.
The Motorola 6800 microprocessor was the first for which an undocumented assembly mnemonic HCF became widely known. The operation codes (opcodes—the portions of the machine language instructions that specify an operation to be performed) hexadecimal 9D and DD were reported and given the unofficial mnemonic HCF in a December 1977 article by Gerry Wheeler in BYTE magazine on undocumented ...
The x86 instruction set refers to the set of instructions that x86-compatible microprocessors support. The instructions are usually part of an executable program, often stored as a computer file and executed on the processor. The x86 instruction set has been extended several times, introducing wider registers and datatypes as well as new ...
The x86 processors support five modes of operation for x86 code, Real Mode, Protected Mode, Long Mode, Virtual 86 Mode, and System Management Mode, in which some instructions are available and others are not. A 16-bit subset of instructions is available on the 16-bit x86 processors, which are the 8086, 8088, 80186, 80188, and 80286.
Pages in category "x86 instructions" The following 53 pages are in this category, out of 53 total. ... HLT (x86 instruction) I. INT (x86 instruction) Intel ADX;
On processors that have a halt instruction that stops the CPU until an interrupt occurs, such as x86's HLT instruction, it may save significant amounts of power and heat if the idle task consists of a loop which repeatedly executes that instruction.
The x86 instruction set has several times been extended with SIMD (Single instruction, multiple data) instruction set extensions.These extensions, starting from the MMX instruction set extension introduced with Pentium MMX in 1997, typically define sets of wide registers and instructions that subdivide these registers into fixed-size lanes and perform a computation for each lane in parallel.
Many of the 8080's core machine instructions and concepts survive in the widespread x86 platform. Examples include the registers named A , B , C , and D and many of the flags used to control conditional jumps. 8080 assembly code can still be directly translated into x86 instructions, [ vague ] since all of its core elements are still present.