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I thought it was a marketing gimmick to get big iron competitors off homebrew risc solutions. Because Intel.

• acdha 3y ago
  When it started, there was concern that CISC x86 was hitting a performance wall and Intel really wanted something which was locked up so other companies like AMD, Cyrix, etc. couldn’t clone it. The part where it went wrong was a highly speculative bet on the academic argument that a simpler CPU with a smarter compiler was the future. HP and Intel bet the farm on that panning out, but they ran into a number of setbacks and the competition wasn’t giving them time to recover. Itanium was late and slower than predicted, and both RISC and x86 got a lot faster since they could focus on features like speculative execution and SIMD while Intel was pouring resources into fundamentals dealing with all of the perils of a new architecture, especially one which has significantly different performance trade offs. The original pitch was that Itanium would be faster, but most people found it to be significantly slower even on native code – compilers weren’t as good at finding instruction level parallelism as hoped – and once you factored in the cost it was irrecoverable: nobody is paying twice as much for a server which is half as fast on the hope that in years to come improved compilers might get closer to parity. The real winner was Microsoft, and to a lesser extent Linux: part of this switch involved a lot of RISC vendors giving up and switching to Windows. Companies like HP, SGI, etc. scrubbed their plans to focus on Itanium systems but they didn’t go back to their proprietary Unix variants.