If there is interest I will put up the HP G/L code on one of my web-
pages. HP/Agilent provides a little support for these old, workhorse
products, but not much. I also have a "fix" for converting the Gerber
output produced by Ultiboard to something which will plot on an
HP7475 in minutes instead of hours.
The old serial plotters go for a few tens of dollars on EBay.
Jack
