On Thu, 15 Mar 2001 09:09:41 +1100, you wrote:

>On 01:08 PM 14/03/2001 -03-30, Fabian Hartery said:
>>Hi Everyone,
>>I have some real strange behavior going on with the dreaded hidden pins.
>>These are being assigned sub-nets and are showing global netlist behavior
>>where none exists. That means, a floating terminal of part 1, pin 2, is
>>shown associated with pin 2 of part 2. I would have suspected that a parts
>>definitions are held in a 'local' definition and not a global one. I can't
>>see  an applicable rule affecting this, unless there is a rub in the
>>protocol of creating a netlist.
>Hidden pins always imply global connectivity (same as power objects).  You 
>can't change it - all you can do is never use hidden pins and make your 
>life easier and better documented.
>Regular readers will know that I am being very constrained as this whole 
>hidden pin thing is one of my *major* hates. 

Yep we heard it - I have used hidden power pins without issue in every
design I have done since Orcad SDT version 2 days. 

I have actually had more hassle with shown power pins on multipart
components where the parts move around on annotation (duplicating power
pins on each part is yuk, and how do you justify showing the same pin 4
times on a schematic?). Also hassle with things like op amps where there is
no space to label the power pins and the typical convention of +ve supply
at the top and -ve at the bottom may have to be broken. 

The only dumb trap people can fall into is making a schematic part with all
pins and calling all the no connect pins NC and hiding them. 

If power supplies are not straight forward then it takes about 30 seconds
to make a copy of the schematic part with power pins showing. 

As for showing no connect pins - it is about as useful as adding a few
ficticious components to the schematic and marking them as not fitted and
nothing to do with the design? 

Elsewhere in this thread Ivan Baggett said 

>[Off topic]  I also hate assembly language code written with macros.  Same
>concept (hidden code).  It makes it very difficult to figure out what's
>really happening.

This is quite telling, and actually exactly wrong - macros and hidden code
make it easy to figure out what is going on - that is the whole point of
using them and the founding principle of all Object Oriented Languages. 

We have a limited capacity to deal with complexity and the complexity of
problems and hence solutions is increasing all the time. The most succesful
way we have come up with for managing complexity involves organising it
into lumps which look simple from the outside. This specifically involves
hiding of information. 

The point is hiding information is not inherently bad - it is powerful part
of information management. 

Cheers, Terry.

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