AMD K6
Marketing Logo
Developer	AMD
Manufacturer	AMD
Type	Microprocessors
Introduction	April 2, 1997 (launch)
Production	1997
Architecture	Pentium-compatible superscalar microprocessors with MMX
ISA	IA-32
µarch	K6
Word size	32 bit 4 octets 8 nibbles
Process	350 nm 0.35 μm 3.5e-4 mm , 250 nm 0.25 μm 2.5e-4 mm
Technology	CMOS
Clock	166 MHz-300 MHz
Package	SPGA-321
Socket	Socket 7
Succession
←	→
K5	K6-2

K6 was a family of 32-bit x86 microprocessors designed by AMD and introduced in early 1997 as a successor to their K5 line. K6 lower cost along with superior performance (comparable or better than Pentium II's clock-for-clock) made these processors a viable alternative to Intel's. K6 gained wide acceptance in the PC market.

Overview

In October of 1995, when AMD was suffering a number of setbacks in their K5 design (so much so that AMD's profitability depended on Am5x86), a small fabless company by the name of NexGen was making headway by announcing their 6th generation x86, Nx686, at the 8th Annual Microprocessor Forum in San Jose, California. The Nx686 was a very advanced microprocessor based on their previous RISC86 microarchitecture which was a RISC core that translated CISC instructions into smaller µops. The chip managed to comfortably take on Pentium, being a superscalar with speculative out-of-order execution and supporting MMX.

Following AMD's late arrival of K5 and additional delays after release due to subpar performance with the first design (SSA/5), AMD was already well into designing their next generation of chips. AMD couldn't afford the same sort of problems with K6 as they did with K5. In 1995 AMD was in bad shape as far as the K5 and K6 designs go; at the same time NexGen had a great product and engineering team but no real outlet to manufacture and sell it (at least not one that could compete with Intel's). On October 21, 1995 AMD announced that they will be buying NexGen for about $857 million in stock.

Following the acquisition of NexGen, AMD simply scrapped their own K6 design and renamed Nx686 K6 instead. The design underwent a number of small modifications: the chip was modified to be bus and pin-compatible with Intel's Pentium, making it a drop-in replacement/alternative to any Intel's Socket 7 motherboard.

Launched in April 1997, the final result was AMD's K6 - an entirely NexGen's designed microarchitecture, bus-compatible, pin-compatible, and software-compatible with Intel's Pentium including superior FPU and MMX support. Selling well under Pentium prices allowed K6 processors to gain widespread acceptance.

Early K6 processors were given PR2 ratings (Pentium II-based performance rating), however the rating system was dropped just a few months later because the chips were performing as well or better than Pentium II processors at the same frequency.