AMD K6

Microarchitecture: K6/Enhanced RISC86

The AMD K6 and its immediate successors, the K6-2(+) and K6-3(+), are not, in fact, designs originating from AMD themselves. Rather, the K6 is a modified core based on NexGen's Nx686 processor, which AMD acquired with their merging with NexGen. This chip and its successors ultimately would provide AMD with the funding necessary for the development of their succeeding K7 architecture, which is now famously known as the Athlon. The series of chips as a whole would serve as AMD's answer to their competitor Intel's Pentium, Pentium II and Pentium III.

Variant: K6
The original K6 core.

Variant: Little Foot
Effectively a die shrink from the original 350nm K6 to 250nm, bringing with it higher clock speeds and lower power consumption.

AMD K6-2

Microarchitecture: K6/Enhanced RISC86

An iterative improvement over the previous K6 chips and a competitor to the Intel Pentium II. The K6-2 introduced AMD's "3DNow!" instruction set extension as a competing alternative to Intel's SSE extensions. The K6-2 also introduced an extension of Socket 7, the last CPU socket to ever be shared by Intel and AMD CPUs. Super Socket 7, as this extension was called, introduced higher processor bus speeds, which allowed the K6 series to remain competitive even against Intel's chips even on the aging Socket 7 and Super Socket 7.

Variant: Chomper
Introduced the 3DNow! instruction set extension.

Variant: Chomper Extended (CXT)
A refresh of the previous Chomper core that supported additional Front Side Bus speeds and clock rates, up to 550MHz officially.

AMD K6-3(+)/AMD K6-2+

Microarchitecture: K6/Enhanced RISC86

Officially marketed as the K6-2+, K6-III, and K6-III+, the K6-3 competed directly against Intel's Pentium III line of chips. A key difference over the previous K6-2 was the inclusion of 256KiB of integrated L2 cache. Any external L2 cache memory integrated into the motherboard would then be utilized instead as L3 cache, as part of AMD's "TriLevel Cache" technology. The K6-3 also implements additional 3DNow! instructions.

Variant: Sharptooth
Effectively a K6-2 core with an integrated 256KiB of full-speed, on-die L2 cache.

Variant: K6-III-P
A mobile variant of Sharptooth.

Variant: K6-2+
Though branded as a K6-2, the K6-2+ is in fact a die-shrunk K6-3 containing 128KiB of L2 cache. It additionally contains AMD's "PowerNow!" power-saving features, as it is officially a mobile chip.

Variant: K6-III+
Released alongside the K6-2+ in April 2000, the only major difference between this variant of the K6-3 is that it includes the full 256KiB of L2 cache as opposed to the 128KiB of the K6-2+.