Intel's flagship CPU chip, introduced in late 2000. The successor to the Pentium III chip, the Pentium 4 features the NetBurst micro-architecture (see NetBurst). All Pentium 4 chips are single core, while dual-core Pentium models go by different names such as Pentium D and Pentium Processor Extreme Edition, all omitting the "4" designation. Available in both 32-bit and 64-bit versions with and without Hyper-Threading, the Pentium 4 was introduced at the end of 2000 with 1.4 and 1.5 GHz clock rates. Speed later reached 3.8 GHz. Pentium 4 chips were first built with 180nm process technology and subsequently shrunk to 130, 90 and 65 nm. From Rambus to DDR Memory Pentium 4 chips support from 2GB to 8GB of DDR memory. Intel's first Pentium 4 chipset, the 850, supported only Rambus memory, but subsequent chipsets, starting with the 845, supported the more common DDR SDRAM. See dual core, Pentium and Pentium Processor Extreme Edition, Pentium 4 Processor Extreme Edition.