The Pentium Pro is a sixth-generation (P6 core) x86 architecture microprocessor produced by Intel in November 1995, and it was originally intended to replace the original Pentium in a full range of applications. While the Pentium and Pentium MMX had 3.1 and 4.5 million transistors, respectively, the Pentium Pro contained 5.5 million transistors. Later, it was reduced to a more narrow role as a server and high-end desktop chip. The Pentium Pro was capable of both dual- and quad-processor configurations. It only came in one form factor, the relatively large rectangular Socket 8.
In 1997, the Pentium Pro was succeeded by the Pentium II processor, which was essentially a cost-reduced and re-branded Pentium Pro with the addition of MMX and enhanced 16-bit code performance. Costs were reduced by using standard SRAM cache chips running at half-speed, which increased production yields. The next year, in 1998, Intel split the market into three segments: budget workstations and home users, higher-end workstations and power users, and multi-processor capable servers. Those segments were served by the Celeron, the Pentium II, and the Pentium II Xeon, respectively.
The Pentium Pro (given the Intel product code 80521), was the first generation of the P6 architecture, which would carry Intel well into the next decade. The design would scale from its initial 150 MHz start, all the way up to 1.4 GHz with the "Tualatin" Pentium III. The Pentium Pro had a theoretical performance of 400 MFLOPS. The core's various traits would continue after that in the derivative core called "Banias" in Pentium M and Intel Core (Yonah), which itself would evolve into Core architecture (Core 2 processor) in 2006 and onward.