How to write Uniprint files. or The Ignorant Man's Guide to Weaving Disclaimer: This is not yet a How-To, not even a mini-How-To. But if I can manage to keep trying and get some work put into it, and if we have less atmospheric electrical activity than we have recently, it just might grow up to be one. First off, this information came about because the Epson 740 met the price-performance ratio I was looking for, and I ASSUMED that since the ESC 600 and ESC 800 were supported, the ESC 740 would be, too. Wrong! So I guess it was up to me. A few evenings with some scratch paper, and then some time on the plane to and from the 1999 International Solid State Circuits Conference in San Francisco, (from Vermont) and I had an Epson 740 functioning under Linux. This work came from examining the upp files that came for the ESC 600 and 800, sort of figuring out what they were up to, and then trying to do the same thing for the 740. So without all of the original Uniprint work by , this never would have even left the ground. A Few Words About Weaving The Epson Stylus Color printers have some number of inkjets, which varies from model to model. Unfortunately, all models have jet pitches which are significantly coarser than the desired resolution. (Except for the ESC 900, which I don't know how to make print at 360*360.) As a result, printing is a combination between stepping the paper in some appropriate pattern, and using the appropriate ink jets. I have worked with three examples, the 600, 740, and 800. To begin with, let's consider 720*720 resolution. The 600 does this in 8 passes. That means that the jet pitch in the print head is 8 times coarser than the dot pitch, or 90 jets/inch. At that same resolut- ion, the 740 takes 6 passes, or 120 jets/inch and the 800 takes 4 passes, or 180 jets/inch. I have reason to believe that the new ESC 900 will take 3 passes, or 180 jets/inch. One way to weave this would be to paint a row, step 1/720 inch, paint the next row, etc, until 8 rows are done, using the 600 for reference. After this, one would step past all that has been printed and begin the next swath. The problem with this scheme is that each head would be printing 8 adjacent rows. If one jet was undersized, there would be fine white lines visible between the printed rows. If a jet was oversized, there would be dark lines. Microweaving It's much better if adjacent rows were never printed by the same jet. That way, things would average out better.