是x86 RISC还是CISC？

Question

根据维基百科,x86是一个CISC设计,但我也听说过/它是RISC.什么是正确的？我还想知道为什么它是CISC或RISC.什么决定设计是RISC还是CISC？它只是微处理器所具有的机器语言指令的数量,还是有任何其他决定架构的特性？

Answer 1

x86是CISC架构.指令数量是一个重要因素,因为所有cisc架构都有更多指令.此外,由于指令在cisc中很复杂,它们可以完成> 1个循环,而在RISC中它们应该是单循环.主要区别在于:

+------------------------------+------------------------------+
| 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,请访问:http: //www-cs-faculty.stanford.edu/~eroberts/courses/soco/projects/risc/risccisc/

Answer 2

早期的x86(8086/186/286/386)绝对是CISC.

但是,更新的处理器可以被视为具有RISC核心的混合处理器

这里另外参考