Please see below.


----- Original Message -----
From: "Ian Wilson" <[EMAIL PROTECTED]>
To: "Protel EDA Forum" <[EMAIL PROTECTED]>
Sent: Monday, October 14, 2002 6:05 PM
Subject: Re: [PEDA] WARNING!!! Junctions at + points can disappear in DXP

> On 03:19 PM 14/10/2002 -0700, JaMi Smith said:
> >The issue is not to win friends and influence people, any more than it is
> >nit pick over spelling.
> Beg to differ - you posted the original message in order to influence
> people. The whole point of a forum like this is to influence people.  The
> whole point of constructive criticism of the CAE program many of use is to
> influence people (Altium programmers and management). Sprays and vitriol
> may influence people, possibly not in the direction intended though - I
> thought Andrew Jenkin's comments were just on the wrong side of the
> border.  Been there myself often enough.

OK, Ian, you lost me here, this is my first entry into the fray on this
thread, and as far as I know, on any related thread.

I just came in at Abd's comments, and backed up to get the whole thread, and
then responded with my response.

It appears that you and I both posted, about the same time, both in response
to Abd, and I just now checked my email and saw two from you on this thread.

> >The real issue is to get the people south of the boarder who don't have
> >inkling of the real issues involved in the real world of electronics to
> >writing software that screws up a perfectly good schematic of an
> >or other symmetrical circuit that legitimately uses a 4 way connection.
> JaMi - please report what Nick Martin has said on this matter to be
> fair.  Though some of this may be subject to the NDA.  But everyone should
> not assume the sensible, sane, discussion on this matter is not being
> listened to.  Just doesn't make good headlines does it...

I will be happy to do this, but please remember that you have asked me to do
this, and I am not trying to dump on anyone here, simply answer your

Please let me reiterate - you asked - please don't jump on me for honestly
responding here below

Ok, to be fair, I will give an example, and not necessarily directly on this
specific topic, but on a very closely related topic, on schematic and logic
symbols in particular, and I am not quite sure who wrote all of the posts,
but some Altium people responded, and I also know that Nick was involved in
this one, although please note, I bit my tongue and stayed out of it.

Let me now direct everyone's attention to the original DXP Tech Forum, and a
few comments that showed up there back in August just after DXP was released
(forgive me while I multiplex here and look for tidbits.)

Go to your DXP Tech Forum Archive, and begin with the thread "Re: [DXP] Bugs
and Missing Capability - no De-morgan [sic] ??"  by Dennis Saputelli, on
8.12. From there the thread appears to be reinitiated by Dennis again on
8.13 under the thread subject of "Re: [DXP] no De-morgan [sic] or IEEE
alternate symbols ?? - the horror".

I would recommend that anyone that is really interested in following this
should first go read all of the posts in the thread, thoroughly and without

Now, without commenting on specifics, I am going to give my impressions of
what the various things in this thread spoke to me, be it right or wrong.

While I did not have the time or the experience with DXP to get directly
involved in the thread at that time (didn't even have it installed), I was
firstly appalled that Altium would delete the availability of a De Morgan
equivalent for any logic symbol. This, in and of itself, speaks volumes to
me about Altiums failure to really comprehend one of the primary purposes of
a schematic or logic diagram, which is to properly and clearly convey the
electrical function of a circuit. In my opinion, many EDA Companies have
lost this perspective of looking at a schematic or logic diagram, or never
ever really had it to begin with, and to me, this truly says that Protel /
Altium is in fact one of those companies.

Secondly, I am also appalled at the number of people who use the
availability to have a De Morgan equivalent within a logic symbol, as an
alternate symbol function. To me, these people asking for trouble, and too
lazy to correctly develop a true alternate symbol, which unfortunately
actually gives some justification for Altiums responses in the DXP forum.

The thing that is truly odd here, is that what really struck me as bizarre,
is something that I am sure everyone involved in the thread will deny the
minute I mention it, yet I believe that any unbiased observer will see upon
examination of the threads, is the fact that everyone involved in the
threads clearly and unambiguously defined and / or accepted the usage of
both "De-morgan [sic]" AND / OR "IEEE" symbols as alternates to "standard"

The funny thing is, none of them appear to seem to think that there is
anything wrong with this assumption, either at that time, and possibly even
now reading up to this very sentence, they do not think there is anything
wrong with this, or really understand that this really reveals that they do
not know much about schematic or logic diagram symbology.

What many people call "standard" or "regular" logic symbols, are in fact
actually "Distinctive Shape" logic symbols, and were originally simply
called logic symbols. With the advent of the "IEEE" style logic symbols,
first comprehensively introduces by TI, it became necessary to distinguish
between the "IEEE" symbols and the "originals", and hence the "originals"
were then specifically named as "Distinctive Shape" logic symbols.

What this is leading up to is this. "Distinctive Shape" logic symbols, and
"IEEE" logic symbols, are each ALTERNATE TYPES OF LOGIC SYMBOLS.

De Morgan, or more properly De Morgans Theorem, can be applied to most LOGIC
FUNCTIONS, irrespective of the TYPE of symbology that used to represent the
function, and thus you may correctly have a De Morgan equivalent of a
"Distinctive Shape" logic symbol, just as correctly as you can have a De
Morgan equivalent of a "IEEE" logic symbol, although the latter is certainly
less common.

The real point here, is that it is apparent that none of the participants of
that discussion appeared to be aware of this, although I am sure that now
they will all deny it at this time and say that I am nit picking, and that
it really does not matter.

Well it actually does matter, but the place that it does matter is right
back there in the area that I am complaining about to begin with, and that
is having to do with the need to understand that one of the primary
functions of a schematic (remember we got here by talking about some places
where a 4-Way connection really should be used) or a logic diagram is to
clearly convey the operation of an electronic circuit, which is in fact the
EXACT FUNCTION AND PURPOSE of a De Morgan equivalent of any logic symbol.

A De Morgan equivalent of a logic symbol is used for absolutely no other
purpose whatsoever except for clarification of a logic function. Period. End
of story. It is only unimportant to those who have lost site of the
"clarification" issue (or never had it in the first place).

Unfortunately, with the advent of modern day CAD systems for the desktop PC
such as OrCAD, (and other offenders including Protel), which for the most
part use a Laser Printer for an output, and the advent of "Hierarchical
Schematics", and "Multisheet Schematics", all of which were brought about by
not being able to get things to be legible and still fit on an "A" size in
the first place, the function of a schematic or logic diagram has degraded
in the hands of the modern "two year wonder" (I believe that that was what
Andrew was really trying to say), whether he be a designer, a programmer, or
a software developer, to be nothing more that a collection of symbols and
lines whose only real function now is to "front end" the "netlist" which in
turn "frontends" other EDA functions such as PCB design.

I believe that it truly is the case that even the people who are writing the
software at Altuim have indeed lost site of the functionality of the
schematic and logic diagram, and it certainly does not say much when all of
the key players and users in these forums are doing "stupid tricks" like
putting an alternate symbol of an op amp in place of a De Morgan functional

Ok, you ask, how do I do it. Well, not to digress, but firstly, due to the
problems with multiple supplies and grounds, especially in the analog arena,
I believe that it is essential that all power and ground pins must be
specifically shown "except for truely standardized logic) and individually
connected to prevent errors. Unfortunately, this tends to add more
information to an already cluttered  up schematic, but it prevents errors.
Second, I make sure that each individual type of op amp has its own specific
symbol, with all pins clearly labeled and all pin numbers clearly shown.
Again, this tends to add a little clutter, but is proven to reduce errors.
Finally, after I make the schematic symbol for an ABC123 type op amp, I make
a copy of it, and edit the inputs to represent the same op amp with the
inputs inverted, and then I rename the copy as ABD123_I, where the "_I"
clearly conveys that the inputs are inverted. I now truly do have an
"alternate" symbol, that clearly has an "alternate" usage, and a symbol that
I can guarantee that no one can ever reverse the pinout on. I know, you are
all going to find something wrong with that, but such is life. I can now
easily train an engineer to use the correct symbol, and since I have
provided him with the alternative, he will actually use it and I don't have
to worry about him flipping the symbol vertically and hooking up the power
and ground backwards, which is real easy for some engineers to do. (I also
believe that it is especially important to label all transistors (including
AJ's transitor variety) and diodes with pin numbers in the symbols due to
common packaging variations.) I know, I am doing it all backwards.

Actually, I think not. When I have an alternate function for the same
device, I make an alternate symbol, and I do not hide it in the De Morgan
function. A De Morgan equivilent of a given function will never electrically
alter the function, as some of you are doing with your op amps.

Please do not construe any of the above to imply that I am against taking
advantage of "pin swapping" (in the sense of traditional "gate swapping"),
where functionally identical pins can be swapped. This can usually be
accomplished by mirrioring only one axis of the symbol, but occasionally
even this demands the use of a true alternate symbol (until DXP Next
Generation, which will handle all of this for us automatically (yeah sure)).

I know that you are all going to now say "but now we can define up to 256
blah blah blah . . . "

The real problem with that is that with the possible exception of true "pin
swapping", and a true De Morgan equivalent, you really do not "need" to be
able to define any other "versions" of a symbol, because all of the
"alternates" truly should be an "alternate symbol". This usually also
applies even when alternating between "Distinctive Shape" and "IEEE" symbols
(unless it can all be done with exactly the same pin locations, etc.) .

Giving you the option of screwing up 256 times instead of one or two is not
what I would consider a real solution to the problem. I actually think that
the "solution" to this problem as I understand it is to be implemented in
DXP is not in fact a soultion but a monumental blunder.

The first step in any real solution is to learn how to draw a schematic in
the first place.

I am sorry, you asked. No offense intended.


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