AMD K8

Lore & Background

The K8 core is very similar to the K7. The most radical change is the integration of the AMD64 instructions and an on-chip memory controller. The memory controller drastically reduces memory latency and is largely responsible for most of the performance gains from K7 to K8. Processors based on the K8 core include the Athlon 64, the first 64-bit consumer desktop; the Athlon 64 X2, the first dual-core desktop; the Athlon X2, a later dual-core desktop with '64' omitted; the Athlon 64 FX, an enthusiast desktop with unlocked multipliers; the Sempron, a low-end, low-cost desktop; the Opteron for the server market; the Turion 64 for mobile computing; and the Turion 64 X2, a dual-core mobile processor.

It is perceived by the PC community that after the use of the codename K8 for the Athlon 64 processor family, AMD no longer uses K-nomenclatures (which originally stood for Kryptonite) since no K-nomenclature naming convention beyond K8 has appeared in official AMD documents and press releases after the beginning of 2005. AMD now refers to the codename K8 processors as the Family 0Fh processors. 10h and 0Fh refer to the main result of the CPUID x86 processor instruction. In hexadecimal numbering, 0F(h) (where the h represents hexadecimal numbering) equals the decimal number 15, and 10(h) equals the decimal number 16. (The 'K10h' form that sometimes pops up is an improper hybrid of the 'K' code and Family identifier number.)

Reader's Guide

The K8 microarchitecture marked a significant shift for AMD by introducing the AMD64 64-bit extension to the x86 instruction set, enabling 64-bit computing on consumer and server platforms. Its integration of an on-chip memory controller was a key architectural change that reduced memory latency and drove most of the performance improvements over the preceding K7 core. The K8 core spawned a wide range of processor families covering desktop, server, and mobile markets, including the first 64-bit consumer desktop (Athlon 64), the first dual-core desktop (Athlon 64 X2), and the enthusiast Athlon 64 FX with unlocked multipliers. The naming convention around K8 later gave way to AMD's use of Family identifier numbers (such as 0Fh) in official documents, with the 'K' nomenclature effectively ceasing after K8. The K8's legacy includes establishing AMD as a competitor in 64-bit x86 computing and setting a foundation for subsequent architectures.

Did You Know?

• The K8 was the first implementation of the AMD64 64-bit extension to the x86 instruction set.
• The K8 core integrated an on-chip memory controller, which drastically reduced memory latency.
• The Athlon 64 X2 was the first dual-core desktop processor based on the K8 core.
• AMD now refers to K8 processors as Family 0Fh processors, where 0Fh equals decimal 15.