Related story: Review of the Cyrix III / Samuel in English
Intel already demonstrated how to make a low-price consumer processor on the basis of a high-end CPU. The Celeron basically is a Pentium III with half its L2 cache. AMD followed along these lines when reducing the Duron's L2 cache to 64 KByte while the Athlon (Thunderbird), the Duron's "big brother", continues to rely on 256 KBytes. The Duron's L2 cache sits directly on the die, too. It runs at the full clock speed of the core.
We put various configurations of the Duron up against its Intel competitors. The Duron CPU we reviewed was a production silicon we obtained from AMD directly.