Thoroughbred 'A' is the first 130nm Athlon CPU. Basically it's a die-shrink from the Athlon 'Palomino' which was used in the first Athlon Mobile 4 and Athlon XP processors.
The die-shrink had several advantages: lower power consumption (and thus a cooler CPU), lower production costs because of the smaller footprint and better scalability. Unfortunately the scalability was a bit dissapointing because the Thoroughbred 'A' didn't really clock well beyond 2000MHz. AMD had been struggling getter the aging 180nm Palomino faster than 1733MHz (XP2100+) and the new 130nm Thoroughbred 'A' as only good for the introduction of the XP2200+ which ran at 1800MHz.
In Q4 of 2002 the improved version, namely Thoroughbred 'B', was available which enabled AMD to release the Athlon XP 2600+ in late August.
The first kind of Thoroughbred processors from AMD. The Thoroughbred is the successor of the Palomino core and uses a 130nm manufacturing process. It's a few weeks newer than this 2100+ Palomino.
A while before the launch of the Thoroughbred CPU people were interested in it's overclock-ability. Rumours were going on that someone was able to overclock it to 2,6GHz or 2,7GHz which sounded surrealistic so some stated that it would rather be 2600+ or 2700+ (which has a lower clock frequency). Later turned out that the Thoroughbred didn't overclock to 2,6GHz and was rather a disappointment as overclocker. It was not until early 2003 when the Thoroughbred B (improved version of the Thoroughbred) started to hit 2,7GHz frequencies and eventually more than 3GHz using LN2 cooling. > Read more