Computer Chess Club Archives




Subject: Re: Introducing "No-Moore's Law"

Author: Matt Taylor

Date: 13:44:12 03/03/03

Go up one level in this thread

On March 03, 2003 at 09:50:12, Robert Hyatt wrote:

>On March 03, 2003 at 02:09:52, Matt Taylor wrote:
>>On March 02, 2003 at 23:43:41, Robert Hyatt wrote:
>>>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...
>>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?
>X86-64 has the _same_ problem.  It has to remain "true" to the Intel X86
>architecture or
>it won't sell at all.  When Intel adds new instructions (CMOV is one example)
>then any
>new copycat chip _must_ support it or it will be broken and have no market.

AMD didn't support SSE for a long time. That didn't slow AMD sales at all. AMD
still doesn't support SSE 2, although the K8 will support it. AMD's sales are
slow for other reasons.

Regardless of x86, the x86-64 is still AMD's architecture. They are no longer
following as they have defined the new rules. The x86-64 is an open architecture
just like Sparc.

>The point being not that AMD is bad, but that they have chosen to cast their lot
>intel in an attempt to usurp part of their market share, which is a perfectly
>valid decision.  But
>it means they will _always_ be following Intel because they have to maintain
>compatibility with the core architecture.

The "core architecture" has not changed in over 10 years. Addition of cmov, SSE,
or whatever else you care to bring up uses a well-defined Intel mechanism that
allows for backward-compatibility. The only change to the core architecture is
that x86-64 is now 64-bits, not 32-bits, and AMD has changed the instruction set
a good deal. Being backward-compatible does not mean they're following Intel.
The x86-64 really isn't following anything.

>As far as 3dnow, it seems pretty "3d dead".  Microsoft will have more to say
>about that since
>they have the dominant compiler project for X86, and if they aren't going to
>produce the
>code natively, nobody is going to care except for a few of us that twiddle with
>asm() stuff
>on our own...

Microsoft has never supported MMX, 3DNow, or SSE in their compiler. That doesn't
make any of them dead. I consider 3DNow dead because Athlon also supports SSE,
but some people -still- use 3DNow. Many games support 3DNow as well as SSE, and
I think games and desktop multimedia were really the primary target of vector
extensions anyway. I don't know whether professional rendering programs like
Lightwave support any vector extensions, though I would imagine they do.


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