Processor Types and Specifications - Upgrading and Repairing PCs - page 111

to be two to as much as ten times faster than the FPU in the 486. In addition, the two
standard instruction pipelines in the Pentium provide two units to handle standard integer
math. (The math coprocessor handles only more complex calculations.) Other processors,
such as the 486, have only a single standard execution pipe and one integer math unit.
To learn more about Pentium processors, including the famous floating-point calculation
flaw,see Chapter3 of Upgrading and Repairing PCs, 19 th edition ,availableinitsentirety
on the disc packaged with this topic.
AMD-K5
The AMD-K5 is a Pentium-compatible processor developed by AMD and available as
the PR75, PR90, PR100, PR120, PR133, PR166, and PR200. Because it is designed to be
physically and functionally compatible, any motherboard that properly supports the Intel
Pentium should support the AMD-K5. However, a BIOS upgrade might be required to
properly recognize the AMD-K5. The K5 has the following features:
• 16KB instruction cache, 8KB write-back data cache
• Dynamic execution-branch prediction with speculative execution
• Five-stage, RISC-like pipeline with six parallel functional units
• High-performance floating-point unit
• Pin-selectable clock multiples of 1.5x, 1.75x, and 2x
TolearnmoreabouttheK5andAMD'sP-Rating systemfornamingtheseprocessors,see
Chapter 3 of Upgrading and Repairing PCs, 19 th edition , available in its entirety on the
disc packaged with this topic.
Intel P6 (686) Processors
The P6 (686) processors represent a new generation with features not found in the previ-
ous generation units. The P6 processor family began when the Pentium Pro was released
in November 1995. Since then, Intel has released many other P6 chips, all using the same
basicP6coreprocessorasthePentiumPro. Table3.13 showsthevariationsintheP6fam-
ily of processors.
Table 3.13 Intel P6 Processor Variations