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This Article was last modified in July, 1998.

Intel's Xeon processor is Intel's highest performing processor, and its introduction extends the price/performance dynamics of the Intel Architecture to new levels of technical and enterprise computing. It is the first in a new family of branded Intel processors specifically designed to offer the memory configuration required by the most demanding applications for mid-range and higher servers and workstations.

The Pentium II Xeon processor is available with large, fast caches (currently up to 1MB running at full CPU speed, with 2MB coming soon.) to keep data flying at super high speed through the processor core. In addition, superior manageability features such as Thermal Protection, Error Checking and Correcting, Functional Redundancy Checking and the System Management Bus help ensure maximum reliability and uptime.

Advanced Management Features
  • Thermal Sensor
  • Error Checking and Correction (ECC)
  • Functional Redundancy Checking
  • System Management Bus

The Xeon CPU is not significantly different from the current Pentium II line because it uses the same P6 core and 100-Mhz input/output bus. But the Xeon does have a larger cache -- up to 2 megabytes of Level 2 cache -- which runs at the same clock speed as the CPU. Current Pentium II chips have 512K of cache, which run at half the clock speed of the CPU. The Celeron, designed for inexpensive home PCs, has no L2 cache. Unlike the Pentium II, the Xeon uses a new type of connector - similar to Slot 1, called Slot 2, which is much bigger.  The Xeon also uses a new chipset - the 450NX (or the 440GX for workstations), which allows for the handling of up to 8GB of RAM, and for other advanced features of the Xeon.

Until the Xeon, the Pentium Pro was the only (sixth generation) Intel x86 CPU that could be used in a system that required more than two processors (the Pentium II was only capable of dual processing), which was why the Pentium Pro was still commonly seen in servers.  The Xeon will finally drive the last nail in the coffin for the aging Pentium Pro, because of it's ability to be used in quad setups and beyond.

Xeon does have some new technologies designed for enterprise servers, where the chips are aimed. One of the more significant functions is PSE36, 36-bit memory addressing technology that lets a Xeon chip access up to 64 GBs of memory. The Pentium II (and all previous processors since the 386), by contrast, can only access 4 GBs of memory. Unfortunately, the 450NX chip set, which will be built into all first-generation Slot 2 motherboards, can only address up to 8 GBs of memory. Future chip sets will be able to take full advantage of the 64-GB range.

Unfortunately, with great performance comes great price.  The Xeon will definitely not been seen in many home PC's, because of it's high price tag - the 512k version will cost $1,124, while the 1-MB cache version will sell for $2,836 (in lots of 1000).


Performance Enhancing Features
  • Incorporates an L2 cache of either 512K or 1Mbyte. The L2 cache operates at the same speed as the processor core (400MHz), making an unprecedented amount of data available to the processor core.
  • Shares data with the rest of the system via the high capacity 100 MHz multi-transaction system bus, another breakthrough technology that extends the potential of superior processing speeds to the rest of the system.
  • Up to 64 GB of memory can be addressed and cached for increased performance and throughput on the most sophisticated applications.
  • The system bus supports multiple outstanding transactions to increase bandwidth availability. It also provides "glueless" support for up to eight processors. This enables low-cost, four-way and 8-way symmetric multiprocessing and offers a significant performance boost for multitasking operating systems and multithreaded applications.
  • PSE36 - An expansion of 36-bit memory support allows operating systems to utilize memory greater than 4 GB, increasing system performance for large workspace, read-intensive applications.

Other significant features:

  • Intel-developed Single Edge Contact (S.E.C.) cartridge packaging enables high-volume availability, improved handling protection and a common form factor for future Intel Pentium II Xeon processors
  • Cluster support, or the capacity to cluster several four-way server systems. This allows customers to scale their Pentium II Xeon processor-based solutions to the needs of their organization

Key features of the Pentium II Xeon processor include:

  • 0.25 micron P6 microarchitecture core featuring Dynamic Execution, operating at 400 MHz
  • 512KB and 1 megabyte L2 cache options
  • Intel’s Dual Independent Bus featuring:
  • 400 MHz L2 cache bus, operating at the same speed as the processor core
  • 100 MHz transactional System Bus and 100 MHz SDRAM and EDO memory support, allowing faster communication between the processor and other parts of the computer system
  • Support for greater than 4GB of memory for servers using Intel® Extended Server Memory Architecture
  • Addressable memory support up to 64GB
  • New System management features via System Management bus (SMbus)

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