Earlier today on Twitter, AMD engineer Phil Park identified a curious nugget of PC architectural history. Bob Colwell (Pentium Pro chief architect) has been posting on Quora. Pentium 4 had a version of x86-64 that was fused off. This design path was axed by the higher-ups at Intel, who clearly feared it would eat into or harm Itanium (profits).
The aim of the game was Intel getting a 64 bit CPU without having to share the instruction set with AMD.
Intel was crossing many lines in terms of the anti-competitive practices they were willing to engage in, of which hobbling their own internal development was probably the least damaging to the market overall.
