The Free On-line Dictionary of Computing (30 December 2018):
(Known as "P6" during development) Intel's
successor to the Pentium processor, in development Jan 1995,
generally available 1995-11-01. The P6 has an internal
RISC architecture with a CISC-RISC translator, 3-way
superscalar execution, and out-of order execution (or
"speculative execution", which Intel calls "Dynamic
Execution"). It also features branch prediction and
register renaming, and is superpipelined (14 stages).
The P6 is made as a two-chip assembly: the first chip is the
CPU and 16 kilobyte first-level cache (5.5 million
transistors) and the other is a 256 (or 512) kilobyte
second-level cache (15 million transistors). The first
version has a clock rate of 133 Mhz and consumes about 20W
of power. It is about twice as fast as the 100 MHz Pentium.
The original 0.35 micron versions of the Pentium Pro released
on 1995-11-01 run at 150 and 166 Mhz for desktop machines and
up to 200 Mhz for servers. Heat disspation is about 20
The Pentium Pro is optimised for 32-bit software and runs
16-bit software slower than the original Pentium. The
successor was the Pentium II.