{{Otheruses3|Instruction}} In Computer_science, an '''instruction''' typically refers to a single operation of a processor within a Computer_architecture. The types of instruction allowed are defined and determined within the particular platform's Instruction_set_architecture (ISA), which also determines register sources and destination operands, and perhaps an immediate field. Machine instructions are numbers represented in binary Assembly_code is a developed form of short code. A portion (field) of the instruction designates the operation to be done and is called an Opcode; since the numeric value of this is not very meaningful to humans, a corresponding short abbreviation is used by Programmers. The size, or "width" of an instruction depends on the architecture of the platform, but it is usually from 4 to 64 Bits wide. The following is an example of a X86 instruction in symbolic Assembler notation: :SHL   AX, 01 '''SHL''' is called the operation, and '''AX''', '''01''' are called Operands. '''AX''' is the name of a register, '''01''' is a constant. In this example, '''SHL''' is a Mnemonic abbreviation for "shift left". The instruction causes the value in '''AX''' to be shifted left by '''01''' bit position. ==See also== *Command_(computing) *Data_(computing) *Machine_language Category:Machine_code Bg:Машинна_инструкция Cs:Instrukce Es:Instrucción It:Istruzione_(informatica) Nl:Instructie_(computer) Ja:命令_(コンピュータ) Pl:Instrukcja_(informatyka)