The nondisclosure agreements and legal forms have expired, so Hardware Central can confirm what CPU buffs have been buzzing about for weeks: AMD's fastest new processor -- the "Palomino" upgrade of its Athlon desktop family -- is named AMD Athlon XP 1800+ with QuantiSpeed Architecture.

Though built on the same 0.18-micron process with the same Socket A interface and 384K full-speed cache as earlier Athlons, the Athlon XP has an extra half million transistors (37.5 million); a thermal diode for improved heat control; and draws roughly 20 percent less power.

Available with a 266MHz front-side bus only, the new CPU adds 52 SSE instructions (3D Now Professional technology) and QuantiSpeed -- AMD's marketing term for a hardware data prefetch, translation look-aside buffers, and superscalar, fully pipelined microarchitecture and floating-point unit. The XP designation stands for "Xtra Performance"; according to AMD's press release, it also conveys "the extreme performance AMD Athlon XP processors deliver for the upcoming Microsoft Windows XP operating system."

The most controversial aspect of the new Athlons is AMD's use of model numbers instead of megahertz (which HwC lists here although the official release does not): the four Athlon XP models are 1500+ (1.33GHz), 1600+ (1.4GHz), 1700+ (1.47GHz), and 1800+ (1.53GHz). OEM prices range from $130 to $252 in 1,000-unit quantities.

AMD says the model numbers, widely thought to indicate equivalent Intel Pentium 4 performance, actually refer to the Palominos' performance relative to earlier or vanilla Athlons. The company has also announced a "True Performance Initiative" campaign to help consumers understand CPU speed issues and develop an accurate measure of processor performance other than megahertz or gigahertz.

AMD quotes product managers from Compaq and Fujitsu Siemens as planning to introduce Athlon XP-powered PCs, and says that Hewlett-Packard, MicronPC, and NEC-CI are also planning to use the new chip. Hardware Central's sister site Sharky Extreme will post a hands-on test of an Athlon XP 1800+ prototype system today.

Meanwhile, AMD and Microsoft announced they will collaborate on marketing the new AMD Athlon XP processor with Microsoft's upcoming Windows XP operating system, which will be available worldwide on October 25.

Eric Grevstad is managing editor of sister site,HardwareCentral.