Pentium 4

Pentium 4 was a line of single-core desktop and laptop central processing units (CPUs), introduced by Intel on November 20, 2000[1] and shipped through August 8, 2008.[2] They had a 7th-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[3] (up to 3.8 GHz) limited only by TDPs reaching up to 115 W in 3.4 GHz –3.8 GHz Prescott and Prescott 2M cores.[4] In 2004, the initial 32-bit x86 instruction set of the Pentium 4 microprocessors was extended by the 64-bit x86-64 set. The performance difference between a Pentium III at 1.13 GHz and a Pentium 4 at 1.3 GHz would have been hardly noticeable. So the Pentium 4 clock frequency needed to be approximately 1.15 higher than a Pentium 3 to achieve the same performance.[5]
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 200 MT/s or 266 MT/s at that time.
Pentium 4 CPUs introduced the SSE2 and, in the Prescott-based Pentium 4s, SSE3 instruction sets to accelerate calculations, transactions, media processing, 3D graphics, and games. Later versions featured Hyper-Threading Technology (HTT), a feature to make one physical CPU work as two logical CPUs. Intel also marketed a version of their low-end Celeron processors based on the NetBurst microarchitecture (often referred to as Celeron 4), and a high-end derivative, Xeon, intended for multiprocessor servers and workstations. In 2005, the Pentium 4 was complemented by the Pentium D and Pentium Extreme Edition dual-core CPUs.