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(Intel Architecture-64) The 64-bit architecture used in Intel's Itanium family of CPU chips. Engineered for server processing, Itanium/IA-64 was designed when millions more transistors on a chip were commonplace, which was two decades after Intel developed its first x86 CPUs. Later on, Intel also upgraded the x86 line to 64 bits (see Intel 64). See Itanium and x86.

Recompilation Required
Although applications written for x86 and HP 9000 computers run intact on IA-64 machines via translation layers (see IA 32 Execution Layer), programs have to be recompiled in order to take advantage of IA-64.

Rather than variable-length instructions as in x86 (IA-32), IA-64 uses fixed-length, four-byte instructions bundled in sets of three "long instruction words." IA-64 uses 256 registers for integer and floating point operations compared to 16 in IA-32.

IA-64 Predicts the Future
To take advantage of an advanced pipeline architecture, IA-64 employs "predication." Both sides of a branch instruction following a compare are executed in parallel. After determining which branch is correct, the results of the other are discarded. IA-64 compilers have to set up the predication; they have to interleave the instructions and add codes that tell the CPU how to execute in parallel. If predication is not set up, the CPU performs a simpler prediction, whereby it executes in parallel the side of the branch that it thinks will be the outcome, not both sides. If it guesses wrong, the parallelism is lost for those few nanoseconds.

IA-64 also supports speculative loading, which loads data into registers before the instructions actually need to process it. Intel brands this parallel architecture "Explicitly Parallel Instruction Computing" (EPIC), and sometimes refers to the IA-64 architecture as EPIC; thus, IA-64 and EPIC are synonymous.
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References in periodicals archive ?
The Intel 64 Fund is a quarter-billion-dollar equity fund that invests in emerging technologies for next-generation servers and workstations utilizing Intel's IA-64 architecture.
"By working with Intel to give developers early access to Itanium processor prototype systems, VA Linux, through SourceForge, gives developers a head start in compiling, testing, and optimizing their applications to run well on IA-64 Linux."
is positioned to be a player in two simultaneous computing revolutions: Linux and IA-64," said Lee Caswell, director of the OEM Solutions Group at Adaptec.
Additionally, as a natural extension of 3Dlabs' role in integrating state-of-the-art workstation graphics technology with Intel's IA-64 advanced architecture, 3Dlabs' drivers for Windows 2000 will be optimized for Intel's Itanium processor.
IBM has taken a leadership role in this effort, while simultaneously hedging their bets with Project Monterey, a joint effort with SCO and Intel to develop an enterprise-strength Unix standard for the IA-64 processor.
Siemens is developing Sparc versions of its Reliant Unix server range and will ultimately migrate to IA-64 platforms running Solaris.
TELECOMWORLDWIRE-(C) 1994-9 M2 COMMUNICATIONS LTD A group of hardware and software vendors have commenced a review of the interoperability guidelines for Intel's IA-64 computing platform architecture called the Developers Interface Guide (DIG64).
Project Monterey will deliver a single UNIX product line for current and future Intel IA-32 and IA-64 systems that will scale seamlessly from entry-level servers to very large enterprise environments.
Compilers are software development tools that translate commands written by programmers into code that can be run on computers, such as Intel's IA-64. Debuggers are also software development tools used by programmers to both speed application development and to make sure applications are running correctly.
KG, Berlin, Germany has announced that its mental ray rendering software product is one of the first workstation applications to run on Intel's first engineering samples of the IA-64 Itanium(TM)-based platform.