Compaq DL590 - HP ProLiant - 1 GB RAM Technology Brief page 5

TC020702TB
T B
ECHNOLOGY RIEF
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In addition, the floating point performance of Itanium processors is significantly better than that of
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today's IA-32 processors. The Itanium processor has two extended-precision and two
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single-precision floating point units, capable of executing up to four extended-precision or eight
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single-precision floating point operations per clock cycle.
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The Itanium processor uses a high-performance architecture, Explicitly Parallel Instruction
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Computing (EPIC), which is based on very long instruction word (VLIW) systems. This
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architecture achieves a new level of parallelism. New parallel-processing features include:
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Hardware support for multiple parallel data streams
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Fewer memory latencies than traditional architectures
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Better anticipation of instruction streams that can be made parallel
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Support of more parallel streams
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A third level of caching
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Making data parallel before it enters the microprocessor
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Because the Itanium processor has the resources to support more registers, functional units, logic,
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instructions, cache, and data, it delivers increased processing power. It also links the program
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compilers more closely to the processor for more efficient execution of parallel instructions and
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. . optimized application performance. Current IA-32 processors, on the other hand, exclusively use
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hardware within the processor to decide which instructions can be executed simultaneously. The
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. . Itanium processor uses a new instruction set designed for optimal performance with the EPIC
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architecture.
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The Itanium processor is also capable of executing IA-32 (x86) instructions, so it accommodates
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the transition from IA-32 environments to IA-64 environments. While running an IA-32
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application, the processor is switched to an IA-32 mode. When the user returns to the 64-bit OS or
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launches an IA-64 application, the processor is switched back to IA-64 mode. For IA-32
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applications running under a 64-bit OS that supports IA-32 applications and drivers, the OS
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manages the processor mode switching. While some 32-bit software is compatible with the
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Itanium processor, applications achieve higher performance when they are ported to 64-bit
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versions.
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Itanium processors are installed in sockets on the motherboard. A new physical form factor
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(Figure 2) provides four times the bandwidth of the 330-contact slot connector design used in
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Pentium II Xeon and Pentium III Xeon processors.
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Figure 2: The Itanium processor uses a new physical form factor.
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