The Pentium II is the second of the P6 series. The Pentium Pro was first. The PII includes MMX instructions and fixes the slow 16-bit performance of the Pentium Pro. It also marked a transition away from socketed CPUs. As in the PPRO, the 512K cache is seperate from the CPU dies, but instead of including it in the same cavity Intel chose to integrate it on a PCB. This allowed them to use commercial (cheaper) cache chips. With this though the cache ran at 1/2 CPU speed.
The PII was originally made on a 0.35u process but transistioned to a much better 0.25u process.
The PII also saw the introduction of a 100MHz Bus with the 350MHz and 400MHz CPUs. -------------- 80522 = 0.35u (Klamath) 80523 = 0.25u (Deschutes) Note: The code names are both rivers in Oregon that I have been on. ------------------------