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At 11:00 AM 9/1/00 +1000, Geoff Harland wrote:
>(On previous occasions when I have
>looked at ASCII format PCB files, I have noticed the additions to the format
>to support the new layers and other new features provided in Protel 99 SE,
>but I either didn't notice the new format for specifying distances, or else
>this has been a change that has occurred with the more recent Service Packs
>released for use with Protel 99 SE.)
Yes, the change is recent.
>What could well be a desirable change though, and which is not inconsistent
>with how distances are now described within ASCII PCB files, would be a
>change in which 10**-5 inches was made equal to 127 Internal Units, in place
>of the present 100 Internal Units.
Absolutely, this is a good idea, for reasons that Mr. Harland well
explained. It would keep absolute accuracy of conversion.
>One consequence of changing the size of the Internal Unit though, (to the
>recommended value of 2 nm, ) is that the maximum working area would be
>reduced from 99.999" by 99.999" to (about) 84.546" by 84.546" (or
>2147.483648 mm by 2147.483648 mm).
Not a problem as far as I am concerned. If I truly wanted to design
something larger, I would scale the design, say by a factor of 10. Protel's
outward .001 mil resolution is overkill with today's technology anyway. For
PC boards, anyway. (But it is useful for a number of secondary reasons....)
marjan@vom.com
Abdulrahman Lomax
P.O. Box 690
El Verano, CA 95433
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