RISC vs CISC

The distinction between RISC and CISC is not a precise one, only a subjective quantitative description.

RISC

Reduced Instruction set.

Has few operations, but performs each one very fast.

One instruction set compiler

Takes it to the limit:

https://en.wikipedia.org/wiki/One_instruction_set_computer

Funny example implementation for C in x86 mov: https://github.com/xoreaxeaxeax/movfuscator

CISC

Complex instruction set.

Lots of operations.

x86 is considered CISC, although it is known that the processor has a RISC core.

ARM is considered RISC.

RISC core

The distinction between RISC and CISC is further blurred by the fact that Intel X86, widely condiered CISC is actually composed of:

• a complex instruction decoder, which transforms complex input instructions into a simpler subset called microcode
• a RISC core which understands the microcode and actually runs it