If you take the *same* circuit and crank up the power, yes *in general*
I would agree (I can think of exceptions in some ultra high frequency
situations).
But, you cannot apply this as a principal of physics when comparing
CPUs. The circuits are not identical. That is why a 2MHz Z80 consumes
more power (Watts) than a 30HMz Dragonball. The Dragonball does not
defy physics, it just uses a lot more efficient transistors.
What I was referring to is that consumption is not the principal problem
inhibiting faster and faster parts. It is the dissipation of energy
when zillions of tiny transistors switch off (as you obviously know,
current resists changes in flow and transistors work 'harder' under
certain conditions.
In other words, the parts are becoming more efficient at an impressive
rate (more computation, less total power consumed), but heat is a big
problem.
We could discuss this in more detail off line. It seems a bit off-topic
for the list.
Best Regards,
-jjf
-----Original Message-----
From: Marty Rice [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, April 25, 2000 10:57 AM
To: Palm Developer Forum
Subject: Re: End Of Dragonball? Palm Shakeup?
From: Fitzpatrick, Joe <[EMAIL PROTECTED]>
> "There is the inconvienient problem with physics. Power consumption
is
> proportional to the SQUARE of the clock rate."
>
> That is completely false, at least with regards to microprocessors.
The
> problem is at the other end. That is why we moved from 5V to 3.3V
> instead of up to 7V.
>
Joe, I agree with you except for this statement. Power consumption in
all
digital circuits goes up proportional to the clock rate - the switch to
low
voltage parts was done so that the faster slew rates needed to run fast
(e.g. 100's of MHz) are possible. A smaller voltage swing results in a
faster transition. It is an incidental result of this (although nice)
that
lower power is also achieved when the clock rate is not increased. But
start cranking up that clock and you'll pull much more current,
regardless
of your voltage rail. i.e. don't confuse voltage with power.
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