For general purpose processors (desktop or server), the primary value is performance (speed). Compilers can be counted on to provide ease of programming. Operating systems can be counted on to provide ease of use for the users of the system that includes the processor.

For embedded processors, values may be much more complex. Speed may not be crucial and other values such as reliability or minimal use of memory may be more important. Although the performance advantages of RISC may not be as important, its simplicity is often desirable.

The RISC philosophy is specifically targetted at high performance. Its fundamental principle is:

• Add complexity only to make common cases faster.

This fundamental principle has two important corollary principles. Observing the corollary principles gives rise to consequences that ultimately account for the improved performance of RISC processors.

The fundamental principle has two important corollaries:

• Instruction operands should be simple.
  • load-store architecture
  • simple memory addressing modes
• Instruction operations should be abstractly simple. If an operation can be broken down into a sequence of simpler instructions, it should only be added as an instruction if it improves overall performance.

Observing the corollary principles usually results in the following consequences:

• Simple, fast control
• Fixed-length instructions
• Easier pipelining
• Easier handling of dependences between instructions

These consequences ultimately explain the higher performance obtained by RISC processors.