Fred,
        I just recently joined this news group so I feel like I am coming
into the middle of a conversation. If I missed something said earlier, sorry.

        1) A Gerber file is basically a list of "brush strokes" that can be
interperted by photo plotters, printers, and other output devices. The
advantage here is that the Gerber file is not dependant on the generating
tools. Oh, sometimes there are difficulties with the various revisions of
the Gerber standard, but any board fabricator worth thier salt can handel
whatever the customer sends them. So, in short, a Gerber viewer should not
care were the Gerber file came from, so long as the Gerber file is a
revision the viewer knows.

        2) Since a Gerber file is a series of brush strokes, there is no
netlist information, nor component information, stored in the file. A given
viewer might be able to high-light all overlaping brush strokes, giving the
illusion of a net, but it couldn't identify a component so there would be no
conection information. So, unless there has been a revision to the Gerber
standard that I haven't heard of, you can not make a reliable net list from
the Gerber file.

        3) See number 2.

>Date:    Wed, 23 Sep 1998 20:25:02 -0700
>From:    Fred Marshall <[log in to unmask]>
>Subject: Gerber / PWB Design Viewers - Searching for
>
>Thanks to the folks who answered my recent question:
>
>"Can anyone recommend a Gerber Viewer that will allow a designer to
>"light up" a single net at a time - that sort of thing?"
>
>What wasn't quite clear to me in many of the answers was:
>
>1)  are the viewers dependent on the tools that were used to generate
>the design or not?
>
>For example, some tools extract a netlist from the Gerber data and then
>can "light up" a net or set of nets - but, it seems that some others
>might rely on a netlist input.  I may or may not have a netlist input of
>the proper form for the tool being recommended.  Thus this new question.
>
>2)  Is the recommended tool capable of dealing with a variety of input
>types and capable of generating a netlist on its own?
>
>3)  Is there any reason why blind vias might perturb the process of
>extracting a netlist?
>
>Thanks!
>--
>Fred Marshall
>VP Engineering
>RGB Spectrum
>950 Marina Village Parkway
>Alameda, CA 94501
>(510) 814-7000
>
-------------------
Martin Spizman
 MEYER SOUND LABS
  (510) 486-1166
    [log in to unmask]

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