utasításkészlet

An utasításkészlet, often abbreviated as ISA (Instruction Set Architecture), is the fundamental interface between hardware and software in a computer system. It defines the set of primitive operations that a processor can execute. Think of it as the vocabulary that the CPU understands. Each instruction in the set represents a specific operation, such as adding two numbers, moving data between memory and registers, or making a decision based on a condition.

The ISA specifies the format of these instructions, including their length, the types of operands they can operate on (like integers, floating-point numbers, or memory addresses), and how they are encoded into binary patterns that the processor can directly interpret. Different processor architectures, such as x86 used in most personal computers or ARM found in mobile devices, have distinct instruction sets.

The choice of ISA significantly impacts a processor's performance, power consumption, and cost. A complex instruction set computer (CISC) typically has a large and varied set of instructions, often performing complex operations in a single step. In contrast, a reduced instruction set computer (RISC) uses a smaller, simpler set of instructions, aiming for faster execution of each individual instruction and often relying on software to combine simple instructions into more complex operations. Programmers and compilers interact with the ISA to translate high-level programming languages into machine code that the processor can execute.