Intel Pentium III Xeon family is a family of high-performance
processors for high-end workstations and servers. The family was
introduced in March of 1999, just a few weeks after introduction of
Pentium III family. The Xeon processors are based on the same
micro-architecture as Pentium III desktop processors, and include
additional features that improve performance of Xeon-based systems.
One of such features is ability to run in 4-way systems (desktop
Pentium III CPUs could run only in 1-way and 2-way systems). The Xeon
processors also have larger level 2 (L2) cache. The microprocessors
are packaged in big and bulky 330-contact cartridge - the same
cartridge that was used for Pentium II Xeon processors.
There are two different core generations in Pentium III Xeon family:
Tanner core. The core includes 16 KB instruction and data caches,
up to 2 MB back-side L2 cache running at CPU frequency, and MMX and
SSE instructions. These Xeon microprocessors are very similar to
Pentium II Xeon
CPUs. The only difference between them is the CPU frequency and
addition of SSE instructions to Tanner core.
Cascades core: this core is very much alike to Pentium III Coppermine
core. All Cascades Xeon processors have level 2 cache integrated on the
processor core and are packaged into the same 330-contact cartridge
as Tanner processor. Cascades Xeons use updated SC330 interface,
which is called SC330.1. New SC330.1 socket is mechanically
compatible with SC330 (Slot 2). It adds a few signals required to
support on-cartridge voltage regulator, it can also support up to two
processors with 133 MHz Front Side Bus. Not all Cascades Xeon CPUs
support 133 MHz FSB though. There are two variations of Cascades
Xeon microprocessors:
Xeons with 133 MHz FSB have the same size of level 2 cache as
Pentium III Coppermine processors, and, like Pentium III desktop
CPUs, these Xeons can work only in single and dual-processor systems.
Essentially, these Xeons are just Pentium III CPUs in Xeon package.
Xeons with 100 MHz FSB have much larger on-die level 2 cache - up
to 2 MB. These processors can be used in 4-way systems.
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