Intel Pentium Pro processor

Intel Pentium Pro was the first processor from the Intel Pentium II processor family. Targeted for the server and workstation market, the Pentium Pro included integrated 256KB, 512 KB or 1 MB L2 cache running at the processor speed. The L2 cache in the Pentium Pro was not located on the same die as the CPU core. The CPU was packaged in a "dual cavity" package, where one cavity contained the processor die and another contained the L2 cache. As all other members of the Pentium 2 family, the Pentium Pro was optimized to run 32-bit applications and, when running in 32-bit mode, it significantly outperformed Pentium and Pentium MMX CPUs at the same clock speed. At the same time Pentium Pro performance with 16-bit applications was poor, and often the processor was slightly slower than similarly clocked Pentium/Pentium MMX processors. Poor performance of the Pentium II core with 16-bit applications was fixed in the desktop Pentium II CPU.

The Pentium Pro processor was the only processor from the Pentium II family that didn't have MMX instructions.