Intel's processer numbering scheme decrypted

AMD quit the Gigahertz race in a half-baked manner back in 2001, and Intel more recently decided that processors should no longer be classified by a GHz designation, but also by new features that provide value to the customer. New features such as the execute disable (XD) bit, EM64T extensions or Enhanced SpeedStep were added - the Athlon 64 already had all of them - and a sequence numbering scheme was introduced. This allowed Intel to tack on a premium price tag to same-clock-speed chips, while tripling the size of its processor portfolio (counting both the older products and the newer model-numbered ones.)