andrew@frip.gwd.tek.com (Andrew Klossner) (01/09/88)
[This isn't very architectural, so follow-ups have been directed to
comp.unix.wizards only.]
"I also see making parts of UNIX (sh ?) in ROM as a bad idea
since it tends to greatly increase the
development/repair/evolution time. If we had to unplug chips
and bring an engineer in every time there is a PTF for a part
of a system, it would cost someone too much somewhere, and the
changes would never get made."
Changing a ROM doesn't have to be complicated. A good example of a
system where it's blessedly easy to change a ROM is the Atari 2600 home
video game system. Shoving a ROM into the slot is easier than loading
a cassette tape deck.
[No, I don't run Unix on my video game. Or my cassette deck. :-) ]
-=- Andrew Klossner (decvax!tektronix!tekecs!andrew) [UUCP]
(andrew%tekecs.tek.com@relay.cs.net) [ARPA]trb@stag.UUCP ( Todd Burkey ) (01/11/88)
[I disagree...this should be in comp.arch...] In article <9601@tekecs.TEK.COM> andrew@frip.gwd.tek.com (Andrew Klossner) writes: > >Changing a ROM doesn't have to be complicated. A good example of a >system where it's blessedly easy to change a ROM is the Atari 2600 home >video game system. Shoving a ROM into the slot is easier than loading >a cassette tape deck. I agree. My wifes' Epson Geneva Portable has the entire OS on ROM (only CP/M, but still...) and she is always popping the Roms out and putting different things in (they have little handles on them and are keyed so you can't stick them in wrong.) I think this works great because 1) she never has to use the slow cassette, and 2) her Roms won't wear out (barring shocks). I also think the manufacturer may do a better job of debugging the original OS if it is released on ROM. Of course, I am biased, since I also own an ST (TOS and GEM on Rom) and really don't miss the old days of having to worry about which version of OS I had to use for which program on my mac, amiga, and even sometimes on the PC. At last count, I still have 7 different startup disks for my mac, about 5 DOS's for the IBM PC, and used to move back and forth between 3 different kickstart/workbench combos on the Amiga (although that has improved lately according to friends). The only thing having the OS on ROM on my Symmetrics system would give me is a nice warm feeling when I think of file security/integrity, or the fun it would be to rebuild things from floppies. What I would really like is to have all of the most commonly used programs on ROM (vi, cc, libraries, etc) for that tiny improvement over disk access speed. That is what really makes my wifes Geneva system nice...she can pop back and forth between wordstar, basic, and a communications program very, very quickly (for CP/M :-) ). -Todd Burkey trb@stag.UUCP
darrylo@hpsrlc.UUCP (01/17/88)
In comp.arch, rdavis@sushi.UUCP writes: > > >>CD ROM roots would be bad because CD ROM's are blindingly slow. > > > > > >Currently true. But don't take the current state-of-the-art as an intrinsic > > >limit. They'll get faster. > > > > According to "CD-ROM: The New Papyrus" by Microsoft Press, faster data > > transfer from CD-ROMs is unlikely because the frequency of the data starts > > to approach the frequency of the servo mechanisms used to keep the optics > > on track and in focus. > > How about if you have more than one read (laser) on the same [ ... ] > PS: I'm not an EE or a CD expert. I just had an idea... How advanced have liquid-crystal lenses become? It would be interesting to see if liquid-crystal lenses could someday be used to replace CD servo mechanisms. Basically, the LCD lens would remain physically fixed in place, and the focal point would be moved in 3D space, not in 2D space (i.e., along the focal axis) like glass-type lenses. Of course, I could be barking up a tree .... -- Darryl Okahata {hplabs!hpccc!, hpfcla!} hpsrla!darrylo CompuServe: 75206,3074 Disclaimer: the above is the author's personal opinion and is not the opinion or policy of his employer or of the little green men that have been following him all day.
przemek@gondor.cs.psu.edu (Przemyslaw Klosowski) (01/20/88)
In article <4530001@hpsrlc.HP.COM> darrylo@hpsrlc.HP.COM (Darryl Okahata) writes: > How advanced have liquid-crystal lenses become? It would be >interesting to see if liquid-crystal lenses could someday be used to >replace CD servo mechanisms. Basically, the LCD lens would remain >physically fixed in place, and the focal point would be moved in 3D space, >not in 2D space (i.e., along the focal axis) like glass-type lenses. > I don't think liquid crystal lenses are a good alternative because they do not exist :^) LQ are good for shutters (modulated transmission). There is though a non-mechanical design: phase-arrayed semiconductor lasers. Remember that the function of the lens is focus the laser on a particular spot of the sample. The same effect can be obtained by modulating the phase of the light emitted from an array of emitters. Big radars work alreadu this way. przemek@psuvaxg.bitnet psuvax1!gondor!przemek
tainter@ihlpg.ATT.COM (Tainter) (01/21/88)
In article <3225@psuvax1.psu.edu>, przemek@gondor.cs.psu.edu (Przemyslaw Klosowski) writes: > In article <4530001@hpsrlc.HP.COM> darrylo@hpsrlc.HP.COM (Darryl Okahata) writes: > I don't think liquid crystal lenses are a good alternative because they > do not exist :^) LQ are good for shutters (modulated transmission). > psuvax1!gondor!przemek Of course they exist. They are a by product of LQ hologram synthesis. One simply makes a 'pin-prick' hologram (which functions as a lense) artificially with your LQ matrix. Admittedly, these LQ holograms are of very poor quality so far, but they might improve to the point of real utility. --j.a.tainter