The Law of Diminishing Returns (CPU Architecture Innovation Steps!)

Single chip CPUs were first produced in 1971 with Intel’s 4004. In the 34 years since then various features have been added to enhance performance and functionality.

• Single chip CPUs started at just 4 bits but rapidly went upwards through 8, 16 and 1979’s Motorola 68000, a 32 bit processor. The first 64 processors did not appear until 1992.

• Cache was next to be added, first in very small quantities (a few bytes in the 68010) but this has been rising ever since then.

• Soon after external devices such as Memory Management Units and Floating Point Units were also integrated.

• The 68040 and 80486 delivered pipelining, this was the beginning of the integration of RISC technologies into CISC chips. Pipelining allows the CPU to operate on different stages of different operations simultaneously - e.g. it can be reading one while executing another.

• Superscalar execution was next, this gave the processors the ability to execute multiple instructions simultaneously. This arrived in the 80586 (aka Pentium) and 68060.

• OOO (Out of Order) execution appeared in the Pentium Pro. Along with it came things like speculative execution and pre-fetching.

• x86 got SIMD / Vector capabilities in increments from MMX onwards. PowerPC got it in one go with the introduction of AltiVec.

• Intel introduced Hyperthreading in a version of the Pentium 4.

• Most recently AMD have lead the way with point to point busses, 64 bits, on-die memory controllers and more recently dual cores.