Reduced instruction set computer

The Reduced Instruction Set Computer (RISC) philosophy is to take the most used instructions and make them efficient and drop the rarely used ones. It is common to have many on chip registers and pipelining to achieve a throughput of one instruction every clock cycle.

Before RISC it was common to cling to the old practices of microcode and complex instructions from before a CPU could fit on an integrated circuit. A state of the art 8 bit CPU could require 200 engineers working for several years to design. A 32 bit RISC CPU can be designed in half the time by only 4 people.