CISC and RISC

CISC, translated into complex instruction set computer. CISC refers to an instruction set with a single instruction and complex operations. Engineers only need to write down simple program codes and hand over complex operations to the processor, but some complex operations take several machine cycles to realize.

Later, engineers found that only 20% of CISC's instructions were frequently used, so they advocated focusing on accelerating common instructions, combining common instructions to form more complex instructions, that is, RISC, and translating them into reduced instruction set computers. RISC selects the instructions in CISC that can be completed in a single machine cycle to reduce the complexity and hand them over to the compiler.

It can be seen that the difference between CISC and RISC lies in the complexity of instructions, not the number of instructions.