🚀 go-pugleaf

To hear all the exotic ideas that came tumbling forward when this topic
first appeared (some of them independently on sci.electronics and comp.lsi,
against my entreaty to keep the discussion on sci.electronics where it
began), one might infer, first, that everyone wants to use a "format" that
is already available to them (no surprise); and, second, that there is no
common vision or assumption about just exactly what this format is 
supposed to DO. Allow me to address this point and then (for now) shut up.

Paul Dietz and several respondents seem to have the very specific idea of
posting *pictures*, i.e., strictly-graphic information, incidentally about
circuits. This of course requires a lot of data and an agreeable format.
On the other hand, I feel I have to point out very explicitly what some
have touched on briefly: that if your real goal is communicating circuits
rather than line drawings, requiring actual graphics is unnecesarily
restrictive and it is foolish to limit yourself to that approach.  Many 
readers have for years been conveying circuits to their CAD software
without so much as a single line being drawn.  Before you dismiss this 
point because it's not what you had in mind, consider that non-graphical
schematics can encapsulate ALL of the real information a reader needs
to reproduce the circuit; they can (as those not familiar may not realize
at all) be readily readable, easy to compose, and self-explanatory with 
the aid of comments (inevitable anyway); they require NO software,
NO graphics device, and NO agreed format; they contain only essentials
(topology, devices and values) and thus require much less net bandwidth
than graphics (while reaching a wider audience); and, finally, we will 
have to use them anyway as a lowest-common-denoinator to back UP any 
graphics format if we ever want our schematics to be acessible to the
(vast majority of) readers who lack graphics devices or software.

I have of course appended an example, but my point transcends that: if the
real interest is in *circuits* rather than general line drawings, and you
want any substantial fraction of your readers to have access to them, then
an accessible, non-graphics format is obvious, easy, and necessary.
(As one dealing daily with circuit hacking for twenty years, I promise
that it doesn't REALLY matter what direction the transistor points in,
or whether that wire runs above or below, much as some people may have
difficulty imagining a circuit not rendered in their favorite format).
I will say that the process is most straightforward with small discrete
circuits like audio or RF circuits or small logic; if you need to show a
big chip in non-graphic form it becomes a tedious netlist -- but then that
situation is not much different with graphics either.

That was about circuits per se. Now I am the first to agree that it is
also nice to communicate pictures of circuits (as long as we keep in mind
that it is a different objective, with greater obstacles). I have no
easy fix to offer of the kind Paul is calling for, but I certainly agree
with others that they payoff is vastly greater in adopting an established
industrial format where all of the hard thinking and mistake-making has
already been done (by people who know what they're doing). To this end I
reiterate my assertion that in the LONG run we must inevitably adopt 
something based on EDIF. Unfamiliar as it might be to many, it's on the
way IN, and it will probably be a lot more familiar to a lot of you in
a few years just in the course of events (just as ASCII is now familiar,
for example, although it brought blank responses when it was new). I 
should not have to mention how much it pays to bank on a universal
standard that's on the way IN.

Here's a little circuit in the already-nearly-universal SPICE-type
syntax (in use already at far more sites than the Usenet reaches, BTW).
I'll explain that each line is a device; the first couple of numbers are
node numbers that the device is connected to; and the last number is
a value. It should be obvious that C's are capacitors and R's are
resistors; standard element codes for other common devices exist and
could be readily summarized in a single posting, along with some other
minor details that, if followed, would permit all of the schematics in
this format to be applied directly to SPICE-class circuit simulator
programs so that people could evaluate them without even building them.

Further comments associated with a circuit will readily clarify it
further to human readers. To draw a picture of such a circuit, you start
by getting an idea of what's going on, helped out by thoughtful comments;
you draw numbered points (nodes) according to where you expect the 
elements to appear; and then you draw the elements connected to the
nodes. The result may look a little awkward on first drawing but hey, 
it's the complete circuit, and it works!

   Bridged-T filter; node 0 is gound, 1 is input, 3 is output

   R1     1     2     4.7 k
   R2     2     3     4.7 k
   C1     2     0     100 pF
   C2     1     3     330 pF

Max Hauser / max@eros.berkeley.edu / ...{!decvax}!ucbvax!eros!max