Intel Itanium 2 (McKinley) processors
Introduction: July 2002
Itanium was the brand name for 64-bit Intel microprocessors that implement the Intel Itanium architecture (formerly called IA-64). Intel had released two processor families using the brand: the original Itanium and the Itanium 2. Starting November 1, 2007, new members of the second family are again called Itanium. The processors were marketed for use in enterprise servers and high-performance computing systems. The architecture originated at Hewlett-Packard (HP) and was later developed by HP and Intel together.
Itanium's architecture differed dramatically from the x86 architectures (and the x86-64 extensions) used in other Intel processors. The architecture was based on explicit instruction-level parallelism, with the compiler making the decisions about which instructions to execute in parallel. This approach allowed the processor to execute up to six instructions per clock cycle. By contrast with other superscalar architectures, Itanium did not have elaborate hardware to keep track of instruction dependencies during parallel execution - the compiler had to keep track of these at build time instead.
After a protracted development process, the first Itanium was released in 2001, and more powerful Itanium processors had been released periodically. HP produced most Itanium-based systems, but several other manufacturers had also developed systems based on Itanium.
The McKinley core
McKinley was the first version of the Itanium 2 processor, manufactured in an 180 nm process. It was released at speeds of 900MHz and 1GHz, with cache sizes of 1.5MB and 3MB, providing a major perforance improvement over the original Itanium. It added hardware support for the branchlong instruction of the IA-64 instruction set. IA-32 performance, while improved, was still only about 25% as fast as a contemporaneous 2.4Ghz Xeon.
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