mel@houxm.UUCP (06/29/83)
Andy, The mouse and lightpen can both be used to point, track, and sweep exactly the same small cursor. The pen diameter doesn't matter, you just tilt it such that it doesn't obscure (the same as you do with your pen or pencil while writing). It is the mark on the phosphor you are looking at, not the pen or mouse. Only the most clodish lightpen programming would require direct, blind pointing of the pen (no cursor). The real troubles with the pen are that you have to pick it up and hold it. And, as you noted, only one button naturally fits. Another factor against the lightpen is that it is almost impossible to keep the things working - in a production environment where there are response delays, the lightpen is what is banged against the table, its cord is what gets twisted and knoted. Of course, keyboards and mice get abused, too. But lightpens seem to be more at hand. Touch screens are a real lose, unless your application is very simple and low resolution. It is very hard to couple your finger to a small spot on the screen. Also, who wants dirty fingerprints all over the screen? The touch screen is great for menu selections from a TV-like presentation - cute, but not as good as real buttons for the "executive" work station - probably useless for production terminal uses. The bit pad has all the disadvantages of the lightpen and the mouse, with no redeeming advantages; except that some can also digitize drawings. (I would discount the character recognition capability, unless you really had an appropriate application for just that.) Joy sticks, thumb wheels, and small trackballs seem to be just too hard to use. Something about their dynamic range. Perhaps someone from human factors could enlighten us further? Arrow keys are awful, I think everybody will agree. I have no experience at all with large track balls -- anyone care to contribute? In my opinion, the mouse is the big win for normal workstation use. The lightpen 2nd rate, and the others below that. This from 18 years of using, observing, designing, and programming graphics and conventional terminal systems. Mel Haas , houxm!mel
pgf@hou5f.UUCP (06/30/83)
Correct me if I'm wrong, but I thought one of the big limitations of the light pen was that it can only point to a bright spot on the phosphor, not a dark spot. That is, without a cursor under the pen, you can only point to objects already there, and can't point to arbitrary locations without doing a "select" operation that flashes the whole screen. Of course, if you add a cursor, you can track it, but probably only slowly, since you have to "drag" it around the screen with you. Paul Fox ABI HO ihnp4!hou5f!pgf
mlm@cca.UUCP (06/30/83)
One point that I havent seen mentioned about light pens yet is that they only work when you have light on the screen. This means that they can only point to bright objects on the screen, and can not draw on a totally blank screen. This may not be too much of a problem if you happen to like black characters on a white background, but is significant for general graphics work. The other general problem with light pens is that unlike mice or tablet puck they dont stay where you leave them, they must be moved from a rest position to an active position for every use. Martin Moeller decvax!cca!mlm mlm@cca (arpa)
CSvax:Pucc-H:Physics:hal@pur-ee.UUCP (07/02/83)
#R:houxm:-45600:pur-phy:7800006:000:557
pur-phy!hal Jul 1 13:22:00 1983
The same restrictions hold for a mouse; without something visible on
the screen, you are working blind. Mouse and lightpen both have to be
connected to something to provide visual feedback. This can be a cursor
(whether a crosshair, arrowhead, or little finger doesn't mattter), window
edge, rubber band, etc. Thus you can point to a "blank" area of the screen
with a light pen since the screen isn't truly blank.
The most convincing argument against the lightpen I have seen so far is
that it may be too tiring for extended use.
Hal
(pur-phy)bernie@watarts.UUCP (07/08/83)
Another factor in the light pen/touch screen/mouse/trackball/... controversy is the question of compatability. Special touch-sensitive screens, light pens, and so on all need to be "wired" in with whatever display you're using. This means they cannot be easily used in conjunction with low-end micros, which don't come with built-in displays. Trackballs and mice are not in any way affiliated with the display; they're simply another piece of hardware that the OS "knows" about. This makes them inherently more 'portable' from machine to machine, resulting in a larger market, resulting in more R&D dollars, resulting in better mice (and trackballs, and...). Something similar is happening with joysticks for the games machines; there are some really nice sticks out there, and they're getting better all the time. --Bernie Roehl P.S. Now that we're getting better mice, someone's bound to suggest better mousetraps...