At 07:27 PM 4/9/01 +0100, Terry Harris wrote:

>The Cadence schematic stuff I have used a little works like this. Every bus
>entry/exit has a numeric tag to identify which member of the bus you are
>connecting. Busses can also be split and merged again with numeric range
>tags. Symbols can even have bus 'pins' a whole 48 bit data bus on a
>component can be connected directly to a bus (obviously no pin number
>information shown).

Ah, hidden pins! That's really what those are. (Though the Cadence 
implementation might well be more sophisticated, like being able to connect 
DATA1-8, hidden, with the bus D[0..7]. Obviously such a scheme could get 
really hairy if the signals were not simply assigned in numerical sequence)

You can do this now by hiding the pins, with the name of the pin being the 
name of the net you want assigned to the pin. Of course, the connectivity 
would be global. It might be nice if there were a hidden pin attribute that 
made a net with sheet-only scope, which could be useful for this as well as 
the hidden power pin problem, where VCC is +5V on one page and +3.3V on 
another.

I'm not entirely thrilled by the idea of hiding pin assignments. It's great 
for making a nice, neat, compact, readable, schematic, but the technicians 
will be sticking pins in voodoo dolls with a picture of your face taped on 
its head. The last thing one wants to do when sweating a deadline, and one 
needs to know what pin net A5 is on, is to have to look it up somewhere 
else than the schematic sheet with the part on it.

But if there were a schematic with many instances of a part, it might well 
be useful to have a small version of a part with such hidden pins. One 
could then have the full symbol in one place, showing all the pins, and 
then the abbreviated version for other instances. It's worth looking into.

[EMAIL PROTECTED]
Abdulrahman Lomax
P.O. Box 690
El Verano, CA 95433


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