根据 Wikipedia,x86 是一种 CISC 设计,但我也听说/读过它是 RISC。什么是正确的?我也想知道为什么它是 CISC 或 RISC。什么决定了设计是 RISC 还是 CISC?仅仅是微处理器具有的机器语言指令的数量,还是有任何其他特性决定了架构?
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x86 是一种 CISC 架构。指令的数量是一个重要因素,因为所有具有更多指令的 cisc 架构。此外,由于指令在 cisc 中很复杂,它们可能需要 >1 个周期才能完成,而在 RISC 中它们应该是单周期。主要区别在这里:
+------------------------------+------------------------------+ | CISC | RISC | +------------------------------+------------------------------+ | Emphasis on hardware | Emphasis on software | | . | | | Includes multi-clock | Single-clock, | | complex instructions | reduced instruction only | | . | | | Memory-to-memory: | Register to register: | | "LOAD" and "STORE" | "LOAD" and "STORE" | | incorporated in instruction | are independent instructions | | . | | | Small code sizes, | Low cycles per second, | | high cycles per second | large code sizes | | . | | | Transistors used for storing | Spends more transistors | | complex instructions | on memory registers | +------------------------------+------------------------------+
如需进一步研究,请点击此处: http ://www-cs-faculty.stanford.edu/~eroberts/courses/soco/projects/risc/risccisc/
于 2012-10-25T14:59:16.477 回答