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>From: Joe Gwinn <joegwinn@xxxxxxxxxxx>
>>From: Jan Steinman <Jan@xxxxxxxxxxxxxx>
>>
>>...on the 680x0, 16/32 bit ops were completely regular -- they just had to be
>>on an even 16 bit boundary.
>
>True. Actually, any 16-bit boundary would work, even or odd. Or by "even"
>did you mean "exact"?
Ah, you caught me mis-using words. Yes, I meant "exact."
But as I recall, when the 32-bit busses came out (68020?), there was a slight
performance penalty for being on odd 16-bit boundaries when fetching 32-bit
quantities. (Assembly code programmers are so anal... :-)
>> >Actually, with modern computers, the memory system speed is more important
>> >than the CPU speed.
>>
>>Exactly! And the new Mac G5 has a 128 bit memory bus that can hit 6.4
>>gigabytes per second! That's nearly four times as fast as the nearest desktop
>>competitor.
>
>So, the new machines will be four times faster than anything else on the
>market?
Certainly it will approach that level on some things. Photshop use (memory
intensive) benches at 2.2 times faster than a dual 3GHz Wintel box. (Thus, my
particular interest.) Some floating point ops are over 10 times faster!
>I would... doubt that such an advantage would long endure. Computer design is
>a leapfrog game.
That's certainly true. However, I'm hopeful the PowerPC architechure has a lot
of "oomph" left in it.
Intel has pushed clock speeds. This has turned out to be a wonderful marketing
ploy -- how can something that runs at "2" be faster than something that runs
at "3"? (The consumers who ask these questions never question how a 600
horsepower diesel engine delivers such power at 2400 rpm, while a 250
horsepower gasoline engine only develops such power at over 4,000 rpm!)
By pushing clock speeds, Intel is going to run into some fundamental limits
quicker than IBM and PowerPC. As it stands, the PowerPC processor consumes only
about half the electrical power as the latest Intel offerings. This means
you'll see faster, less battery-hungry portables in the Mac line than in the
Windows world.
Besides thermal problems, lower clock speeds are more amenable to better use of
silicon. Intel processors waste a lot of design effort and real-estate dealing
with timing issues that don't exist at lower speeds. For example, it is easier
to implement parallelism and wider, more numerous ALUs with lower clock speeds.
There seems to be considerable room for growth here!
>
>I would not buy a computer that came out a week ago. Too much risk of design
>or manufacturing flaws.
Yea, for those who value safety over excitement, that may be a better goal.
Certainly in the chaotic Windows world, that mind-set has been holding back
innovation, since "new" ideas take longer to catch on. (Case in point: Intel
invented USB, but until Apple daringly put it into every computer as a standard
port, there was essentially no support or devices for it. Now every Wintel box
has it, thanks to Apple.)
However, Apple has done a wonderful job of keeping their "early adopters"
happy. I bought their first 17" monitor, which had problems. They voluntarily
extended the warranty from one to three years, and completely replaced the
monitor with a brand new one after nearly three years! I only recently retired
it (high voltage power supply out) nearly ten years after initial purchase.
(Most monitors in full-time use have a useful lifetime of only about three
years, so I tripled my value on that deal, even though it cost 1.5x as much as
a "no-name" monitor at the time.)
>...digital cameras seem to need replacement every two or three years, just
>like computers.
According to an independent survey (IDC) Apple computers have a useful lifetime
nearly twice that of Wintel machines. Average time-to-replace for Wintel was 28
months, vs 47 for Apple. I'm beating the average with my five-year-old 400 MHz
G4 (2GB RAM) that I'd continue to use for a few more years if it wasn't for
being able to stuff more RAM in the G5.
Finally, I predict that as Moore's Law progresses, we'll begin to see floating
point used more in digital imagery. Current imagery is hamstrung by limited
dynamic range -- 8 bits per color, or essentially 8 stops, similar to slide
film, but considerably less than negative film. There's no coherent standard
among digicams for 16 bit color -- they each have their own proprietary "raw"
format.
Now imagine an image format that would allow essentially any combination of
aperture and shutter speed. It would put an end to pseudo-film-speed ratings on
digicams. Even 16-bit floating point could provide 128 stops of dynamic range!
If floating point imagery catches on soon, PowerPC will gain a HUGE advantage
over Wintel, much like the advantage they currently enjoy in scientific
simulation and visualization -- a market Apple currently owns, due to the
floating point performance of PowerPC.
All in all, it's an interesting time to be around. Whether one prefers Windows
or not, I think most people are glad Apple is out there, nipping at Wintel's
heels... :-)
--
: Jan Steinman -- nature Transography(TM): <http://www.Bytesmiths.com>
: Bytesmiths -- artists' services: <http://www.Bytesmiths.com/Services>
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