Re: Nature isn't so sloppy

From: Michael Wilson (
Date: Fri Sep 09 2005 - 13:30:07 MDT

Phil Goetz wrote:
> A silicon chip operates with about a 10-volt difference between
> its two states, in order to be almost error-free.

Eh? Classic TTL operates at 5 volts. Normal discrete CMOS
goes down to 3 volts. Modern CPUs use between 0.9 volts (e.g. ultra
low voltage Pentium M) and 1.9 volts (e.g. heavily overclocked
Pentium 4).

> We humans have gone from a reliability of .9 to 1-10^-14

Reliability is not solely dependent on voltage. CPU voltages
have been decreasing over the last twenty years while
per-gate reliability has been going /up/, not down.

> in exchange for an increase in power requirements of 4 orders
> of magnitude.

Power dissipation is dependent on current times voltage, not
just voltage, and current drain is variable with switching
technology. Some of the fastest internal components of the
Pentium 4 actually operate on voltage differentials of 0.3
volts, but draw /more/ power than the standard 1.4v logic.
Most of the power dissipated by the brain is unrelated to
ionic current flow anyway.

> Because of the error rate of neurons, you need 1 or 2 orders
> of magnitude more of them for reliable computation. But nature
> still comes out 2 orders of magnitude ahead in terms of power
> dissipation per gate.

Where are you getting this stuff? Do you actually have any
familiarity with digital electonics?

 * Michael Wilson

To help you stay safe and secure online, we've developed the all new Yahoo! Security Centre.

This archive was generated by hypermail 2.1.5 : Wed Jul 17 2013 - 04:00:52 MDT