[sdiy] Is everything digital?

[Tim Daugard]

> The real point is that you use the model most suited to your problem.
>
> Digital design -> boolean model.
> Parasitics control for internal chip modelling -> analogue and RF
models.
> Quantum devices -> quantum model.
> Audio design -> analogue model.
>
> Reality itself is none of these, although the quantum model seems to
be the
> best one so far for sub-atomic processes. For all anyone knows reality
is

Actually the four listed are a continous spectrum, each an abstration of
the level below it. And we don't know how many levels lower there are or
how many levels higer we will end up with.

Level
1    ???
2    Quantum devices -> quantum model.
3    Parasitics control for internal chip modelling -> analogue and RF
models.
4    Audio design -> analogue model.
5    Digital design -> boolean model.
6    Operating systems?
7    ???

I started electronics at level three (RF) with no knowledge, moved up to
level 4 and discovered a little knowledge, became a paid expert at level
5, discovered I had no real interest at level 6. I started moving back
done the spectrum learing more about level 4 and 3 and reading with
interest about level 2 and 1.


> Meanwhile *what defines a system as digital isn't discrete voltage
> distributions, but the use of formally defined symbolic logics and
coding
> systems.*
>
>   So I wouldn't consider sending eight voltage levels down to a wire
to be
> digital - unless you have some kind of eight-level logic system at the
> other end performing symbolic operations. Similarly a trinary system
is
> only digital if it uses some variant of trinary logic. If it does none
of
> these things, it's quantised, not digital.

The eight voltage levels code one of eight switches pressed by a foot.
At the other end is a controller that puts out a low or high level
signal on one of eight pins representing the switch pressed. The two
wire three level system works the same way. This means we have go from
digital - eight switches, either on or off, to analog - a current
through a wire (or two wires) that creates a voltage level across a
resistor (or two) at the other end that is compared with references, to
digital - 8 voltage levels that are high or low representing the state
of eight mechanical switches.

My favorite digital part is the 4066. It is stubornily digital. I took
one and slowly varied the voltage to it to see where it switches. It has
a wide range of voltages that it just ignores on the control inputs. It
is firmly in realm 5.

Tim Daugard
AG4GZ 30.4078N 86.6227W Alt: 3.7 M
http://home.sprintmail.com/~daugard/synth.htm