There was a time when processors were relatively simple. You had a model name (Pentium, Athlon, Celeron…) and a clock speed, and that was pretty much it. With the Athlon XP, things started getting complicated. Suddenly, the number at the end of the name was no longer the clock speed. At first, you could sort of crib up a cheat sheet by starting with 1533MHz for the 1800+, then adding 66MHz for every additional 100 in the model number. Pretty soon, however, there were multiple chips with the same model number that differed in clock speed, cache size, and bus speed. Today, AMD and Intel have abandoned clock speed entirely on some chips in favor of three-digit model number systems that are more or less arbitrary. It\’s gotten to the point where you need a secret decoder ring just to understand what you\’re getting in a modern CPU.