The Pentium Pro suffered from two substantial problems. First, the production costs of the integrated L2 cache did not drop at the usual rate for single chip designs. The Pentium Pro started expensive, as top of the line CPUs always do. But the price did not drop as rapidly over time as single chip CPU designs did. More important, the Pentium Pro parallel processing/instruction lookahead was inhibited when 8 or 16 bit subsets of registers were referenced. The result was that the Pentium Pro often executed older "Legacy Code" little, if any, faster than a cheaper Pentium of the same clock speed did. Intel's benchmarks show a Pentium Pro to be about 40% faster than a Pentium at the same clock speed. That is possibly valid for pure 32 bit code. Intel also claims a Pentium Pro executes three instructions per clock cycle, but that appears to be a maximum rate that is unsustainable except possibly by carefully designed benchmarks.
The Pentium Pro was introduced as a 150MHz/166MHz CPU and was later released at 180 and 200MHz ratings. A 200MHz version with a 1024K integrated L2 cache was also released. A 333MHz Pentium Pro override CPU for Socket 8 (Pentium-Pro) motherboards was released in September 1998.
Return To Index Copyright 1994-2008 by Donald Kenney.