Author: Matt Taylor
Date: 23:09:52 03/02/03
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On March 02, 2003 at 23:43:41, Robert Hyatt wrote: <snip> >Intel _defines_ the X86 architecture, because they _are_ the X86 >architects. Anybody making compatibles (AMD) is _following_. Which means >they will always be "behind". Because Intel will change the specs, and start >shipping chips, and AMD has to quickly catch up. That's just the way it is >when you are copying your competition's product exactly... <snip> Oh, oh, but this isn't completely true anymore. In the days of the Pentium, AMD and Intel weren't the only two x86 chipmakers. There was also Cyrix, IDT, Evergreen, and a few others. I do not recall many details, but 3DNow was part of a bigger open extension to x86 backed by everyone except Intel, and Intel agreed to remain compatible even if they wouldn't support it. Essentially it meant any vendor could propose and implement an extension to the x86 ISA. The extension opcodes were put in the 0F 0F opcode map. 3DNow was the first and AFAIK the only extension proposed in this consortium. All those other vendors are no longer on the x86 playing field, but Intel still "respects" in a manner that agreement. They will never support 3DNow, but they will never break it either. Also, there is the x86-64. I suppose you could consider it a seperate ISA, but I don't see it as being any different from what was already happening to x86. Furthermore Sparc, MIPS, and others have done the same thing -- complete backward compatibility in their ISA. Ironically Intel was building an x86-64 chip. I've heard since that they've canned the project. You can't blame them; isn't it rather embarassing when you're following someone else regarding your own architecture? -Matt
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