Re: gEDA-user: PCB drill file question

[Rick Collins <gnuarm.2007@xxxxxxxxx>]

At 12:13 PM 5/7/2008, you wrote:

>I made the change, but the spec they reference merely says that TZ
>means "trailing zeros are unneccessary".  It does not mean they must
>be omitted, just that if there are less than six digits, the program
>assumes that the trailing zeros are the missing ones.  Since we
>provide all six digits all the time, our drill coordinates are
>unambiguous either way.

It's pretty mind boggling how a simple effort to save storage can 
mess up so many people and so many systems and end up costing tons of 
money.  All of this is because the originators of the drill file 
format didn't want to include a decimal point in the number.  Of 
course, even with a decimal point, there would still be the issue of 
whether it is in inches, mils, mm or furlongs.  I am sure the idea of 
actually stating in the file what the units are would be unthinkable 
for a CAD developer.

The output from FreePCB includes comments to indicate all of the 
details of the drill tools.  Sometimes reloading this info into GC 
Preview confuses it and it reads the comments as drills.  I end up 
with holes of 10 inches rather than 10 mils.  I guess comments are 
not universal in Excellon format.

Then at the other end of the spectrum is the GPX format for GPS 
information which is very verbose.  At least no one is ever confused 
about the number of trailing zeros in GPX.

Rick

Arius - A Signal Processing Solutions Company
Specializing in DSP and FPGA design      URL http://www.arius.com
4 King Ave                               301-682-7772 Voice
Frederick, MD 21701-3110                 301-682-7666 FAX



_______________________________________________
geda-user mailing list
geda-user@xxxxxxxxxxxxxx
http://www.seul.org/cgi-bin/mailman/listinfo/geda-user