Bakin%HI-MULTICS@sri-unix.UUCP (01/18/84)
From: Jerry Bakin <Bakin @ HI-MULTICS> I just wanted to "point" out that trackballs have been used on Radar Screens for many years. Ever been on a plane in a radar covered controlled airspace? Air Traffic Control uses the trackball to pick out blips from the noise and get them computer identified. The displays I've seen were at least ten years old if not older, and the software was running on 1965 vintage Sperry Univacs. The trackball with a MINIMAL amount of motion lets one travel around the screen and pick out various blips, letters, regions, etc. I'm afraid I can't cite the reference, but in the last Sig-Graph proceedings is a study citing trackballs as one of the most efficient and human oriented input devices around (If not the best, certainly better than mice.) A comment was made that keys give you a finer, more discrete control than do mice. Certainly having a mouse on a pad can give one the illusion that you are tied to an absolute coordinate system, but the trackball software can be completely relative. If you are in a text editor, allow only discrete horizontal cursor movement; you might find the trackball easier to move over a character than when pressing a key. Similarly for vertical movement, allow only discrete line movements, and round the trackball motion to the nearest line. Again, for certain commands like "cut-and-paste-box" where one needs to delineate an area, project the trackballs actual motion onto a polygon of the default type; to designate a box, mark the diagonal corners with the track ball, and have the software figure out the box associated with that. Circles can have centers and radii delineated, or have three points picked out for them. Other shapes of polygon can have all the vertices picked, with lines drawn between them. Enough about that, it seems clear that various applications require different input models, but I think that can be often be implemented in reasonable software than different hardware. On the topic of right and left handedness, I have seen many trackballs (for home video game use and for professional workstations) that come attached to a cord and can be placed anywhere convenient. Jerry. <Bakin at HI-Multics>