Re: gEDA-user: gEDA and PCB ------

[Stephen Meier <smeier@AlchemyResearch.com>]

Well (my understanding) PCB uses a data object called flags. The flags 
are esentially a 32bit (length ?) unsigned integer. Some of the bits in 
the flag are used to determine for each layer if a via is passing 
through a metal polygon. Others of the flags determine if the via has a 
thermal connecting it to the polygon. So if this structure was continued 
a 64 layer version would require 128 bits for the layers + the other 16 
flags. FOr buiried vias the via would have to have some way of knowing 
if it passed through a layer at all.

Steve Meier


Bob Paddock wrote:

> On Thursday 07 October 2004 10:37 pm, DJ Delorie wrote:
>  
> > > 8 layer board which really isn't enough.... time to get PCB to have a
> > > reasonable number of layers... yes yes i know it will be a lot of work.
> > >      
> > We were just talking about this yesterday.  I have some ideas about
> > implementing it.  I think the tricky part is deciding how many layers
> > to allow, or if it needs to be dynamic, and if so, how do you adjust
> > the number of layers?
> >    
> The is admittedly a response based on no knowledge of the internals of PCB.
>
> If a board is built in layers there are a few layers that are always unique,
> such as the silk screen, top paste, bottom paste etc.  All other layers will
> be a trace layer.
>
> You are never going to have an internal paste layer for example.
>
> So after handling the unique layers does not unlimited trance layers fall out 
> for 'free'?
>
>
>