Re: gEDA-user: PCB suggestion

[John Dozsa <jdozsa@xxxxxxxx>]

> 
> harry eaton wrote:
> 
> >It's not true that pcb has a "fundamental" limit of 8 layers. There are 8
> >copper layers. There are TWO silkscreen layers IN ADDITIONto the 8 COPPER
> >LAYERS. You can draw lines, arcs and polygons on the silk layers. It's
> >fairly straightforward to add several non-copper layers for things like
> >keep-outs, outline, or the mask layers. The hard part is implementing the
> >functionality associated with those layers. It's more of a "fundamental"
> >limit to go beyond 8 copper layers but then nobody has ever, to my
> >knowledge, built an 8 layer board with pcb. I know of a few 6 layer boards,
> >many 4 layer boards, tons of double-sided boards and few single-sided boards
> >but nothing beyond 6 layers.  It is rare indeed that more than 8 copper
> >layers are required. Usually when 10 and 12 layer boards are made it is
> >because the designers are lazy.
> >

Almost all the replies on this topic suggest or imply the need to change
the underlying board layer data structure.  I'm very new to PCB and gEDA
but a fundamental stated requirement is an open ASCII database.  Let me
make a suggestion for future PCB architects.  Consider adopting the
Mentor Graphics (MGC) Board Station ASCII database.  This has become a
defacto standard for many translators between high end pcb tools.  In
fact one company, Intercept, sells a pcb tool that reads and writes the
MGC ASCII data files.  Surely the MGC data structure would meet all the
needs of PCB.  Yes, the data structure started out as proprietary but it
may not be so currently.  A search on "board station ascii database"
will provide many links.  Just think many more users of PCB there could
be if the layout tool they use at home could be compatible with the one
at work.

John Dozsa