Pentium 4 Processor; Processor Overview - HP Compaq dx6100 Series Technical Reference Manual

Processor/Memory Subsystem

3.2 Pentium 4 Processor

These systems each feature an Intel Pentium 4 processor in a FC-LGA775 package mounted with
a passive heat sink in a zero-insertion force socket. The mounting socket allows the processor to
be easily changed for servicing and/or upgrading.

3.2.1 Processor Overview

The Intel Pentium 4 processor represents the latest generation of Intel's IA32-class of processors.
Featuring Intel's NetBurst architecture and Hyper-Threading technology, the Pentium 4
processor is designed for intensive multimedia and internet applications of today and the future
while maintaining compatibility with software written for earlier (Pentium III, Pentium II,
Pentium, Celeron, and x86) microprocessors. Key features of the Pentium 4 processor include:
Hyper-Threading Technology—The main processing loop has twice the depth (20 stages) of
earlier processors allowing for increased processing frequencies.
Execution Trace Cache— A new feature supporting the branch prediction mechanism, the
trace cache stores translated sequences of branching micro-operations ( ops) and is checked
when suspected re-occurring branches are detected in the main processing loop. This feature
allows instruction decoding to be removed from the main processing loop.
Rapid Execution Engine—Arithmetic Logic Units (ALUs) run at twice (2x) processing
frequency for higher throughput and reduced latency.
1-MB Advanced transfer L2 cache—Using 32-byte-wide interface at processing speed, the
large L2 cache provides a substantial increase.
Advanced dynamic execution—Using a larger (4K) branch target buffer and improved
prediction algorithm, branch mis-predictions are reduced by an average of 33 % over the
Pentium III.
Enhanced Floating Point Processor —With 128-bit integer processing and deeper pipelining
the Pentium 4's FPU provides a 2x performance boost over the Pentium III.
Additional Streaming SIMD extensions (SSE2)—In addition to the SSE support provided by
previous Pentium processors, the Pentium 4 processor includes an additional 144 MMX
instructions, further enhancing:
Streaming video/audio processing
Photo/video editing
Speech recognition
3D processing
Encryption processing
Quad-pumped Front Side Bus (FSB)—The FSB uses a 200-MHz clock for qualifying the
buses' control signals. However, address information is transferred using a 2x strobe while
data is transferred with a 4x strobe, providing a maximum data transfer rate that is four times
that of earlier processors.
3-2 361834-001 Technical Reference Guide