Pentium 4

Pentium 4 was a line of single-core desktop, laptop and entry level server central processing units (CPUs) introduced by Intel on November 20, 2000 and shipped through August 8, 2008. They had a seventh-generation x86 microarchitecture, called NetBurst, which was the company's first all-new design since the introduction of the P6 microarchitecture of the Pentium Pro CPUs in 1995. NetBurst differed from P6 (Pentium III, II, etc.) by featuring a very deep instruction pipeline to achieve very high clock speeds. Intel claimed that NetBurst would allow clock speeds of up to 10 GHz in future chips; however, severe problems with heat dissipation (especially with the Prescott Pentium 4) limited CPU clock speeds to a much lower 3.8 GHz.

In 2004, the initial 32-bit x86 instruction set of the Pentium 4 microprocessors was extended by the 64-bit x86-64 set.

The first Pentium 4 cores, codenamed Willamette, were clocked from 1.3 GHz to 2 GHz. They were released on November 20, 2000, using the Socket 423 system. Notable with the introduction of the Pentium 4 was the 400 MT/s FSB. It actually operated at 100 MHz but the FSB was quad-pumped, meaning that the maximum transfer rate was four times the base clock of the bus, so it was marketed to run at 400 MHz. The AMD Athlon's double-pumped FSB was running at 100 or 133 MHz (200 or 266 MT/s) at that time.

Pentium

Pentium is a brand used for a series of x86-compatible microprocessors produced by Intel since 1993. In its current form, Pentium processors are considered entry-level products that Intel rates as "two stars", meaning that they are above the low-end Atom and Celeron series but below the faster Core i3, i5 and i7 lines as well as the high-end Xeon processors.

The current Pentium processors have only the name in common with the early ones, and are in fact based on the Intel Core architecture, typically implemented by lowering the clock frequency and disabling some features, such as hyper-threading, virtualization and, partly, L3 cache.

The name Pentium is originally derived from the Greek word pente (πέντε), meaning "five" (a reference to Intel's fifth-generation microarchitecture employed on the first Pentium processors), with the Latin ending -ium.

Overview

During development Intel generally identifies processors with codenames, such as Prescott, Willamette, Coppermine, Katmai, Klamath or Deschutes. These usually become widely known, even after the processors are given official names on launch.

Pentium III

The Pentium III (marketed as Intel Pentium III Processor, informally PIII, also stylized as Pentium !!! ) brand refers to Intel's 32-bit x86 desktop and mobile microprocessors based on the sixth-generation P6 microarchitecture introduced on February 26, 1999. The brand's initial processors were very similar to the earlier Pentium II-branded microprocessors. The most notable differences were the addition of the SSE instruction set (to accelerate floating point and parallel calculations), and the introduction of a controversial serial number embedded in the chip during the manufacturing process.

Processor cores

Similarly to the Pentium II it superseded, the Pentium III was also accompanied by the Celeron brand for lower-end versions, and the Xeon for high-end (server and workstation) derivatives. The Pentium III was eventually superseded by the Pentium 4, but its Tualatin core also served as the basis for the Pentium M CPUs, which used many ideas from the P6 microarchitecture. Subsequently, it was the Pentium M microarchitecture of Pentium M branded CPUs, and not the NetBurst found in Pentium 4 processors, that formed the basis for Intel's energy-efficient Core microarchitecture of CPUs branded Core 2, Pentium Dual-Core, Celeron (Core), and Xeon.

Pentium II

The Pentium II brand refers to Intel's sixth-generation microarchitecture ("P6") and x86-compatible microprocessors introduced on May 7, 1997. Containing 7.5 million transistors (27.4 million in the case of the mobile Dixon with 256 KB L2 cache), the Pentium II featured an improved version of the first P6-generation core of the Pentium Pro, which contained 5.5 million transistors. However, its L2 cache subsystem was a downgrade when compared to Pentium Pros. In early 1999, the Pentium II was superseded by the almost identical Pentium III, which basically only added SSE instructions to the CPU.

In 1998, Intel stratified the Pentium II family by releasing the Pentium II-based Celeron line of processors for low-end workstations and the Pentium II Xeon line for servers and high-end workstations. The Celeron was characterized by a reduced or omitted (in some cases present but disabled) on-die full-speed L2 cache and a 66 MT/s FSB. The Xeon was characterized by a range of full-speed L2 cache (from 512 KB to 2048 KB), a 100 MT/s FSB, a different physical interface (Slot 2), and support for symmetric multiprocessing.