Quilted Dies of CPU & RAM

[Dave Long]

>> In an industry that only clocks progress on linear semi-log plots
>> true innovation has become rare -- it's far too risky at the high
>> end.
>
> Right --- it's the anti-Innovator's-Dilemma.  As long as focusing on
> making stuff smaller can get you 50+% improvements every year, you'll
> beat all the Teras and Symbolicses just by doing that.

In DSP-land (the last refuge of VLIW?) strange innovations can find a  
home.

A couple of years ago* I'd wondered about gray-coded PC increments.   
Well, the DSP people haven't gone that far, but they do offer the  
option of bit-reversed autoincrementing index registers.  By counting  
left-to-right (x000, x100, x010, x110, x001, x101, x011, x111, x000...)  
one can get various power-of-two circular buffers "for free".

That may seem like a lot of trouble to save a mask op, but there's a  
good market reason to provide the feature: bit reversal simplifies  
twiddling FFT butterflies.

-Dave

:: :: ::

* "patricia indices for directed graphs"
http://lists.canonical.org/pipermail/kragen-discuss/2002-February/ 
000739.html