Disclaimer: I'm a theist but not of the Abrahamic faiths. I have minor biblical scholar and scriptural skills. Also I am not a scientific/legal or
medical expert in any field. Beware of my Contagious Memes! & watch out that you don't get cut on my Occams razor.All of this is my personal
conjecture and should not be considered the absolute or most definitive state of things as they really are. Use this information at your own risk! I
accept no liability if your ideology comes crashing down around you with accompanying consequences!
An Evolved Silicon Circuit!
(unfortunately document pics are unavailable in html version but you can download the original file
from the top of the supplied web page!). Note original document has a problem with some words containing the letter "f" so be aware ok.
I came across this article in some science magazine (New Scientist I think? Sorry I can't remember!) and it wasn't to hard to hunt it down from
Having only read the NS'ists journo's (???) version I was looking for any discrepency with what I remembered from the magazine article and was
mildly surprised to find out that the original document completely confirmed what I had read previously.
Below I quote some of the more salient points of the document.
"By generation 1400, the neat behaviour for the 1kHz input had been aban-
doned, but now the output was mostly high for the 1kHz input, and mostly
low for the 10kHz input. .. with very strange looking waveforms. This behaviour was then gradually improved. Notice the waveforms at generation 2550 |
they would seem utterly absurd to a digital designer. Even though this is a digital FPGA, and we are evolving a recurrent network of logic gates, the
gates are not being used to ‘do’ logic. Logic gates are in fact high-gain arrangements of a few transistors, so that the transistors are usually
saturated | corresponding to logic 0 and 1. Evolution does not ‘know’ that this was the intention of the designers of the FPGA, so just uses
whatever behaviour these high-gain groups of transistors happen to exhibit when connected in arbitrary ways (many of which a digital designer must
avoid in order to make digital logic a valid model of the system’s behaviour).
This is not a digital system, but a continuous-time, continuous
valued dynamical system made from a recurrent arrangement of high-gain groups of transistors | hence the unusual waveforms."
"Fig. 7 shows the functional part of the circuit that remains when the largest
possible set of cells has been clamped without a[ff]ecting the behaviour. The cells shaded gray cannot be clamped without degrading performance,
even though there is no connected path by which they could in[fl]uence the output | they were not present on the pruned diagram of Fig. 6. They must
be in[fl]uencing the rest of the circuit by some means other than the normal cell-to-cell wires: this probably takes the form of a very localised
interaction with immediately neighbouring components. Possible mechanisms include interaction through the power-supply wiring, or electromagnetic
coupling. Clamping one of the gray cells in the top-left corner has only a small impact on behaviour, introducing either unwanted pulses into the
output, or a small time delay before the output changes state when the input frequency is changed. However, clamping the function unit of the
bottom-right gray cell, which also has two active connections routed through it, degrades operation severely even though that function output is not
selected as an input to any of the NEWS neighbours: it doesn’t go anywhere.
This circuit is discriminating between inputs of period 1ms and 0.1ms using
only 32 cells, each with a propagation delay of less than 5ns, and with no o-chip components whatsoever: a surprising feat. Evolution has been free
to explore the full repertoire of behaviours available from the silicon resources provided, even being able to exploit the subtle interactions between
adjacent components that are not directly connected.
The input/output behaviour of the circuit is a digital one, because that is what maximising
the [fi]tness function required, but the complex analogue waveforms seen at the output during the intermediate stages of evolution betray the rich
continuous-time continuous-value dynamics that are likely to be internally present."
Personal Disclosure: All above quotes were cut and pasted directly from document and were edited to fix typos i.e. [fi]tness etc and to emphasize what
I believe are highly salient points in bold
Edited to star and flag. Well done OP.
[edit on 22-5-2009 by OmegaLogos]