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Subject: Re: Thoughts about board representations...

Author: Robert Hyatt

Date: 05:19:17 02/11/00

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On February 11, 2000 at 00:50:06, Tom Kerrigan wrote:

>On February 10, 2000 at 23:21:09, Robert Hyatt wrote:
>
>>On February 10, 2000 at 22:03:24, Tom Kerrigan wrote:
>>
>>>On February 10, 2000 at 17:50:54, Robert Hyatt wrote:
>>>
>>>>There are pros and cons for all implementations.  The pros for bitmaps don't
>>>>become apparent until they are run on a 'native' architecture (64 bit machines).
>>>>When all is said and done, it is likely that both approaches are going to end
>>>>up pretty much equal, except for the 'data width' problem.  IE an 0x88 program
>>>
>>>But you can look at the "data width" problem from the other direction: bitmaps
>>>don't run efficiently on non-64-bit processors.
>>>
>>>I like having a program that runs reasonably well on a small processor with
>>>small memory...
>>>
>>>-Tom
>>
>>
>>Two important points:  (1) 64 bits are the future, not 32 bits,  So in 5 years,
>>32 bits will probably be like 286's today.
>>
>>(2) super-scalar architectures have a problem keeping both pipes full.  Bitmap
>>programs aren't as inefficient as first suspected, as they offer thousands of
>>places where two 32 bit and/or/xor/etc operations are needed to complete a 64
>>bit operation.  Super-scalar eats that alive and makes the penalty much less
>>than expected.  IE I'll bet a bitmap program actually executes 2 instructions
>>per clock way more than a non-bitmap program, which means part of the 'loss'
>>is covered by clever hardware...
>
>I was thinking more about the 68000 in the PalmPilot and the various RISC
>processors in Windows CE computers...
>-Tom


You can obviously forget about the 680x0's.  :)  However, I'd expect most
new RISC designs to do a pair of instructions at a time.  Of course, I don't
really follow the 'blender-type processors' very closely.  :)  I'm more
interested in the other end of the spectrum.



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