Computer Chess Club Archives




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

Author: Jeremiah Penery

Date: 14:38:23 03/05/03

Go up one level in this thread

On March 05, 2003 at 11:45:20, Robert Hyatt wrote:

>On March 05, 2003 at 01:19:12, Jeremiah Penery wrote:
>>On March 04, 2003 at 23:06:39, Robert Hyatt wrote:
>>>On March 04, 2003 at 19:22:50, Matt Taylor wrote:
>>>>Nonsense. 486 is all you have to support to be compliant with the full ISA.
>>>You remind me of my son.  :)
>>>To wit:  when the "walk" light comes on, he is going to walk across the
>>>street because he _has_ the right of way.  I keep telling him that he is
>>>right of course, and one day he might end up _dead_ right.
>>>I personally look before walking regardless of the color of the light.  I look
>>>before I leave when a light turns green, to be sure some idiot is not going to
>>>run the light and make _me_ "dead right".
>>>And that is where we are here.  You want to advertise that a machine is
>>>equivalentto intel, but faster and cheaper, feel free.  And if you want to stand
>>>on the fine print "but if a program uses cmov without checking the CPUID
>>>processor capability bits it is a bad piece of software."  But the _customers_
>>>will think the machine is broken, and _they_ are the ones you are trying to
>>>market to.  You end up right.  Dead right.
>>>There is "right" and there is "right".
>>When you don't check the CPUID flags before using certain instructions, you are
>>the one walking across the street without checking for traffic.
>You think the average programmer understands that?  I don't think the average
>even understands assembly language, much less that different processors might
>have different
>instruction sets even though they are called "compatible".  When AMD says the K6
>is compatible
>with the PII, but faster/cheaper, then I expect it to be _compatible_.  As will
>most software
>developers.  How many times have _you_ looked at .S output from gcc to see what
>it produces?  I do it all the time and _I_ didn't think about an "equivalent
>cpu" being _almost_

Did AMD specifically say the K6 was P2 compatible, or just a general Intel
compatible?  If they specifically stated P2+ compatibility, I might agree that
they made a mistake.

>If everyone was a compiler expert, this might be forseeable.  But they aren't.
>And I doubt
>most would think that -target=pentiumII would break a processor that is supposed
>to be
>Can I say more?

A lot of the average programmers probably don't even know to use a specific
processor target (when using GCC), or they use some other compiler.  I'd expect
someone who uses specific processor targets in their compile to have some basic
understanding of assembly.

>For the streetlight issue, the streetlight is not hanging over the street in
>plain sight.  It is
>buried under the light pole, with a door with a combination lock on it that has
>to be opened
>so it can be seen.  Do you expect John/Jane Doe to know that when there is no
>sign on the
>pole that says "look here for compatibility issues"???
>I don't.

I'm not sure I expect Jonn/Jane Doe to understand that you have to even look for
traffic, whether the light says 'WALK' or not.  Obviously, there are a lot of
people who fit in that category.

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