Advanced Micro Devices Inc (AMD)

[SemiconEng]

No, AMD64 is not x86 with 64-bit extensions. AMD64 is a full 64-bit architecture that happens to offer compatibility to existing 32-bit x86 code.

Your use of the phrase "with 64-bit extensions" is FUD in that it may be taken as meaning that the 64-bittedness of AMD64 is incomplete, only offering extensions in some of the areas needed to move to a full 64-bit architecture.


Ummmmm......

http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/x86-64_wp.pdf
Advanced Micro Devices, Inc. x86-64TM Technology White Paper
Key extensions to the reliable, proven, high-performance x86 instruction set not only preserve full compatibility between 32- and 64 bit environments, they also enable 32-bit applications to move up the performance ladder right along with other advances in technology...........

Extending x86 for the 64-bit World
AMD's 64-bit strategy is a straightforward extension to the current x86 instruction set. The methodology is similar to that used to extend the 16-bit architecture to 32-bits.

For operating system and application providers, development can continue uninterrupted and unburdened by transition issues and support for the 64-bit extensions in the x86-64 technology can be provided at their own pace..........

The new register extensions added via the new REX prefix add eight 64-bit GPRs (R8-R15), eight 128-bit Streaming SIMD Extensions (SSE) registers (XMM8-XMM15), and widens all
GPRs and the instruction pointer to 64 bits.