The Classic Athlon is a slot A processor, the new Thunderbird is either slot A or socket A. The Thunderbird has 128K of L1 cache and 256K of L2 cache on die running at the full processor speed. The Classic Athlon has 512K L2 cache (not sure of the L1 cache) running at 2/3, or sometimes even less, of core speed. Also, the transistors on the new Thunderbird chip 0.18 micron (not exactly sure on this unit, micron seems rather small, but this is probably a good thing). Of course, if you're looking to read up on these processors, the site you're reading from will always tell you which is which

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