aglew@urbsdc.Urbana.Gould.COM (10/17/88)
..> Multiple heads per arm >>[Henry Spencer] >>the Fujitsu Eagle has two >>heads per surface on its linear actuator. Not a new idea. > >(Darn, I wish I had the balls to say "Uh, Henry,"...) > >Actually, mulitiple heads per surface is an old idea. It used to be quite >common to have "head-per-track" drives. Of course these were generally >single platter machines. I believe the reason for shifting to a multiple >platter "head-per-surface" scheme was cost. > >Actually, there are still a few applications where head-per-track drives >are still used. I believe Univac (err, Sperry, errr, Unisys) makes one >for military aircraft. 100 MB as I remember. > >The problem with placing multiple heads on a *moving* actuator is that each >head adds mass. It may not have to move as far, but it's slower getting >started (for a given servo system) and slower stopping. Any physicists >want to talk about the tradeoffs between moving a large mass a short distance, >and moving a small mass a long distance? > >Rick Farris rfarris@serene.cts.com voice (619) 259-6793 I suppose that head per track drives have gotten scarce because of smaller track spacing? I've always wondered why disk arms are not simply lined all the way along with read/write heads at the closest spacing optical lithography can provide. Either in silicon (maybe a segment every 4 inches) or some other substrate. True, you couldn't make such a long arm fly evenly, but you'd just have to lower one part at a time, which would probably be easier than moving the whole arm. Or, fly the heads high, read from multiple heads simultaneously, and remove cross track interference from the signal for the head you want to read. NB. I nothing *NOTHING* about disk drives. The above is idle speculation. aglew@gould.com (now Motorola MCD CUDC)
grunwald@m.cs.uiuc.edu (10/18/88)
Actually, Mathematica already has a command, called TeXForm, that outputs the (you guessed it) TeX form of a Mathemaica command. There's also CForm, FortranForm, OutputForm and InputForm, plus a few others. I've actually got a Mathematica function that outputs a Mathematica 2-d graph using TeXForm to the pictex macros (although it's far from perfect). While the final output representation is PostScript, the internal representation is much higher-order (i.e. lists of Polygons, etc).