X86-Secret : ES Zone
P-Pro 166 MHz 512K ES  (Week 09, Year 1996)   
KB80521EX166 Q0929 512K - I609201Q-0014 - Intel '94 '95 - I565-0326

The Pentium Pro was very expensive at launch time and only intended to be used on server and high-end workstation. All the P6 line began on November, 1995 with the Pentium Pro. This engineering sample comes with 512 KB of L2 cache and a clock speed of 166 MHz (66.6 * 2.5 MHz). The core stepping used in this sample is sA1 and the CPUID is 0x617.