RE: gEDA-user: 74xx symbols

["EATON,JOHN (HP-Vancouver,ex1)" <john_eaton@hp.com>]

-----Original Message-----
From: Chris Ellec [mailto:chris.ellec@aegisdevices.com]
Sent: Wednesday, July 31, 2002 9:48 AM
To: geda-user@seul.org
Subject: Re: gEDA-user: 74xx symbols


<One of my design right now has both 5V and 3.3V, with half the logic 
<using one supply and the other half using the other supply. So I have to 
<  make sure the parts have the right power connections. You can't do 
<that  if the part definition is glued to Vcc.


This adds yet another contraint on pin/package swapping. Before you can swap
between two different packages you need to check that they are both using
the same supplies.

When you have mixed supplies or a board where part of it is shut down then
you need a schematic that clealy shows the boundries between the regions or
you can have all sorts of problems.

John Eaton