Why Itanium Failed

Intel and Hewlett-Packard formally announced their joint IA-64 architecture in October 1997, after collaborating since June 1994. The bet was bold: replace the aging x86 instruction set across servers, workstations, and eventually desktops with a clean-sheet 64-bit design built around EPIC (Computing) — Explicitly Parallel Instruction Computing, a derivative of VLIW (Very Long Instruction Word). The core idea: stop spending billions of transistors on hardware that dynamically reorders instructions at runtime, and instead let the compiler statically schedule instruction-level parallelism at compile time. Intel's John Crawford led Merced's design with HP veterans of the PA-RISC and EPIC research programs. The plan unraveled at the compiler. Static scheduling requires the compiler to predict, at build time, what will actually happen at runtime — which branches will be taken, which loads will miss the cache, which memory accesses will alias. Real programs are too dynamic for that. Out-of-order superscalar designs in x86 chips like the Pentium Pro and later AMD K8 solved the problem in hardware, at runtime, with information the compiler never has. Donald Knuth's verdict was blunt: the compilers EPIC needed were 'basically impossible to write.' The first Itanium chip, Merced, shipped on May 29, 2001 — three years late, underwhelming in benchmarks, and saddled with an x86 emulation mode that ran legacy code at roughly Pentium-class speeds. Meanwhile AMD took the opposite bet. Its AMD Opteron processor, launched April 22, 2003, implemented x86-64 — a backwards-compatible 64-bit extension of the existing x86 ISA. Customers got 64-bit address space without rewriting, recompiling, or emulating anything. Within a year Intel quietly cloned the extension as EM64T (later Intel 64) and shipped it on Xeon. The 'Itanic' coinage — a Usenet quip from the day the name was announced — became consensus. By 2007 Itanium had effectively lost the general server market; its remaining buyers were HP-UX, OpenVMS, and NonStop customers locked to HP's enterprise platforms. Intel stopped accepting new orders on January 30, 2020, and shipped the last Itanium chips on July 29, 2021, ending a 24-year program that had once been positioned to define the next half-century of computing.