Hardware Reference
In-Depth Information
Intel's change from using numbers (386/486) to names (Pentium/Pentium Pro) for its
processors was based on the fact that it could not secure a registered trademark on a number
and therefore could not prevent its competitors from using those same numbers on clone chip
designs.
The first processor in the P6 (686) family, called the Pentium Pro processor, was introduced in 1995.
With 5.5 million transistors, it was the first to be packaged with a second die containing high-speed
L2 memory cache to accelerate performance.
Intel revised the original P6 (686/Pentium Pro) and introduced the Pentium II processor in May 1997.
Pentium II processors had 7.5 million transistors packed into a cartridge rather than a conventional
chip, allowing the L2 cache chips to be attached directly on the module. The Pentium II family was
augmented in April 1998, with both the low-cost Celeron processor for basic PCs and the high-end
Pentium II Xeon processor for servers and workstations. Intel followed with the Pentium III in 1999,
essentially a Pentium II with Streaming SIMD Extensions (SSE) added.
Around the time the Pentium was establishing its dominance, AMD acquired NexGen, which had been
working on its Nx686 processor. AMD incorporated that design along with a Pentium interface into
what would be called the AMD K6. The K6 was both hardware and software compatible with the
Pentium, meaning it plugged in to the same Socket 7 and could run the same programs. As Intel
dropped its Pentium in favor of the more expensive Pentium II and III, AMD continued making faster
versions of the K6 and made huge inroads in the low-end PC market.
In 1998, Intel became the first to integrate L2 cache directly on the processor die (running at the full
speed of the processor core), dramatically increasing performance. This was first done on the
second-generation Celeron processor (based on the Pentium II core), as well as the Pentium IIPE
(performance-enhanced) chip used only in laptop systems. The first high-end desktop PC chip with
on-die full-core speed L2 cache was the second-generation (Coppermine core) Pentium III introduced
in late 1999. After this, all major processor manufacturers began integrating L2 (and even L3) cache
on the processor die, a trend that continues today.
AMD introduced the Athlon in 1999 to compete with Intel head to head in the high-end desktop PC
market. The Athlon became successful, and it seemed for the first time that Intel had some real
competition in the higher-end systems. In hindsight, the success of the Athlon might be easy to see, but
at the time it was introduced, its success was anything but assured. Unlike the previous K6 chips,
which were both hardware and software compatible with Intel processors, the Athlon was only
software compatible and required a motherboard with an Athlon supporting chipset and processor
socket.
The year 2000 saw a significant milestone when both Intel and AMD crossed the 1GHz barrier, a
speed that many thought could never be accomplished. In 2001, Intel introduced a Pentium 4 version
running at 2GHz, the first PC processor to achieve that speed. November 15, 2001 marked the 30
th
anniversary of the microprocessor, and in those 30 years processor speed had increased more than
18,500 times (from 0.108MHz to 2GHz). AMD also introduced the Athlon XP, based on its newer
Palomino core, as well as the Athlon MP, designed for multiprocessor server systems.
In 2002, Intel released a Pentium 4 version running at 3.06GHz, the first PC processor to break the
3GHz barrier, and the first to feature Intel's Hyper-Threading (HT) Technology, which turns the
processor into a virtual dual-processor configuration. By running two application threads at the same
