Re: gEDA: Proposal: Make symbol files nestable (was: Type numbers for transistors)

[Brendan J Simon <brendan_dot_simon-at-NOSPAMbigpond_dot_com>]

J.D. Bakker wrote:

> Instead of the current situation, where we have a 7400.sym, a 74LS00 
> .sym, a 74HC00.sym etc, all of which effectively have 95% overlap, 
> wouldn't we be better off with:
>
> NAND2.sym:
> <drawing and pin definitions for a NAND2>
>
> 7400_generic.sym:
> C 0 0 1 0 0 NAND2.sym <for lack of a better #include directive>
> numslots=4
> slot1=1,2,3
> slot2=4,5,6
> slot3=9,10,8
> slot4=12,13,11
> <power and ground nets, if desired>
>
> SN74AC00PWR:
> C 0 0 1 0 0 NAND2.sym
> device=SN74AC00PWR
> footprint=TSSOP-14
> manufacturer=Texas_Instruments
> url="http://www-s.ti.com/sc/psheets/...
>
> The same goes for transistors, diodes, LEDs and the like. This would 
> IMO solve a lot of problems by abstracting symbols from devices. 


I think this is a very sensible idea.  It sounds like the "correct" way 
to go.  Is this how most commercial schematic capture, simulators, and 
pcb suites work ???

Does it make sense to have BOTH schemes available.  I ususally know 
exactly what components I wish to use when I design a board, so I place 
the components in the schematic and then create the netlist.  Then I can 
go to the pcb tool and route the board.
Is this the way most people work ?
If so, is having a generic logic gate symbol an advantage ?  
I guess it makes the schematic easier to understand.  eg. if a signal 
needs to be inverted then place a single NAND gate or an INVERTER.  The 
design is easier to understand for someone else looking at the 
schematic.  I guess it's a matter of setting the right attributes to map 
it to a real physical device.  Smart packages can assign these 
automatically and even swap device parts, and even devices, where required.

> I know that in the Open Source/Free Software tradition I should have 
> attached a patch at this point. Sorry, no time yet. It's a poor 
> excuse, but it's the best one I have. 

Yes true, but there is no harm running the idea past everyone before 
hand.  The idea may get sufficiently poo-pooed that your time may have 
been wasted.

Brendan Simon.