Re: gEDA-user: Heavy Symbols and such

[Dave N6NZ <n6nz@xxxxxxxx>]

DJ Delorie wrote:
> Not directly.  I've built parts with "slots" for various input pin
> permutations.

I just realized a few days ago how that trick could be used for pin 
swapping something like a two-input NAND.  And then just last night I 
was doing pin swapping to get better routability.... on a 32kx8 SRAM. 
Let's see... 8 data lines, 15 address lines... 2^23 slots.... ummmm...

The phrase "doesn't scale" comes to mind.

There is a level of abstraction missing.  Something like a "permutable" 
attribute. So a 74as30 might have:

permute=a:1,b:2,c:3,d:4,e:5,f:6,g:11,h:12

as a default, mapping pin names to pin numbers.  The "net list tool" 
could munge the attribute to a new mapping and then back-annotation is 
simply replacing the attribute with the new mapping.  gschem needs some 
smarts similar to slotting to put the right pins on the schematics.

-dave



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