a186@mindlink.UUCP (Harvey Taylor) (07/26/90)
[I know this article probably belongs in alt.exotic.hardware or
something, but I think the people who could answer the question(s)
are here.]
I just received the March 8, 1990 Electronic Design [don't ask me;
ask the snails] and there is an article about using Scanning-Tunnelling
Microscope (STM) technology to make pits in silicon suitable for a
mutated type of CD-ROM. They (Philips Research Laboratories) are
looking at increasing the data density by approximately 10,000. That
would mean a Terabyte CD-ROM. They're currently making holes 0.6 nm
deep and 10 nm across.
Now this is still in the research stage. So all the caveats
applicable to such work apply. There is no product proposal. It may not
be feasible. How would you ever mass produce them?
Still it would be nice.
What I am wondering is, has anybody tried to project what might be
the maximum possible data density achievable (on a plane)?
(This shades into nanotech.)
How many atoms do you have to (re)move to constitute a pit, for a
range of materials? Metals, semiconductors, plastics ...
Blue Sky mode on:
Wouldn't it be nice to be able to get the kind of storage capacities
a 3D structure would bring? Any proposed mechanism?
What might the maximum possible data density in a cube be?
<-Harvey
"Nothing belongs to you more properly than your dreams" - Nietzche
Harvey Taylor Meta Media Productions
uunet!van-bc!rsoft!mindlink!Harvey_Taylor
a186@mindlink.UUCPsysmgr@KING.ENG.UMD.EDU (Doug Mohney) (07/27/90)
In article <2635@mindlink.UUCP>, a186@mindlink.UUCP (Harvey Taylor) writes: > > mutated type of CD-ROM. They (Philips Research Laboratories) are > looking at increasing the data density by approximately 10,000. That > would mean a Terabyte CD-ROM. > Now this is still in the research stage. So all the caveats > applicable to such work apply. There is no product proposal. It may not > be feasible. How would you ever mass produce them? > Still it would be nice. Until the disk crashes ;-)
cik@l.cc.purdue.edu (Herman Rubin) (07/28/90)
In article <2635@mindlink.UUCP>, a186@mindlink.UUCP (Harvey Taylor) writes: .................... > What I am wondering is, has anybody tried to project what might be > the maximum possible data density achievable (on a plane)? Several years ago, I remember hearing that the densest storage material by far was photographic film. Unfortunately, the positioning problem made it almost impossible to read quickly. Densities of 10^8 bits/sqare inch were available then, and presumably this could be increast by a few powers of 10. What is the situation now? Has any progress been made in this direction? -- Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907 Phone: (317)494-6054 hrubin@l.cc.purdue.edu (Internet, bitnet) {purdue,pur-ee}!l.cc!cik(UUCP)
lindsay@MATHOM.GANDALF.CS.CMU.EDU (Donald Lindsay) (07/30/90)
In article <2635@mindlink.UUCP> a186@mindlink.UUCP (Harvey Taylor) writes: > What I am wondering is, has anybody tried to project what might be > the maximum possible data density achievable (on a plane)? Beats me. However, I would certainly hope that the access mechanism involves fewer moving parts than it does now. Specifically, it would be nice if we scanned a laser beam over the media, rather than rotated the media. Or, at least, did the "head" movement that way. There was hope for this sort of thing, a decade ago, and somehow it never happened. I believe that the best spatial modulators had very limited angular effect: perhaps we should be trying to shrink the CDROM disks, just as we've been shrinking the magnetic disks. Which reminds me, what ever happened to the idea of a "head stick", i.e. many thin-film magnetic heads, fabricated onto a rigid bar? I realize that head yields were awful at one time, and I realize that disks used to be great big things. But now, surely, it's time to think of tiny little head-per-track disks. As for DRAM ... if we get to 64 Mb/chip, that should give about an order of magnitude improvement in system-level packing density. As an optimist, my long-term hope is for more like three orders of magnitude, or four. However, this extrapolation doesn't have enough redundancy to please me. That is, I can see a way it could happen: but I can't see several independant ways of it happening. So, it might not happen: we might only get two orders of magnitude. -- Don D.C.Lindsay
sysmgr@KING.ENG.UMD.EDU (Doug Mohney) (07/31/90)
In article <10048@pt.cs.cmu.edu>, lindsay@MATHOM.GANDALF.CS.CMU.EDU (Donald Lindsay) writes: >In article <2635@mindlink.UUCP> a186@mindlink.UUCP (Harvey Taylor) writes: >> What I am wondering is, has anybody tried to project what might be >> the maximum possible data density achievable (on a plane)? > >Specifically, it would be nice if we scanned a laser beam over the >media, rather than rotated the media. Or, at least, did the "head" >movement that way. There was hope for this sort of thing, a decade >ago, and somehow it never happened. I believe that the best spatial >modulators had very limited angular effect: perhaps we should be >trying to shrink the CDROM disks, just as we've been shrinking the >magnetic disks. Thought someone was going to do this with Extabyte-like technology, so you'd get a Terabyte per cartridge on a "tape."
aglew@oberon.crhc.uiuc.edu (Andy Glew) (07/31/90)
>Which reminds me, what ever happened to the idea of a "head stick", >i.e. many thin-film magnetic heads, fabricated onto a rigid bar? I >realize that head yields were awful at one time, and I realize that >disks used to be great big things. But now, surely, it's time to >think of tiny little head-per-track disks. I periodically ask disk engineer types about this. Usually the answer comes back "aeronautics". You don't just want many heads, you want many heads each flying very close to the disk. With a rigid bar you get a lever effect on the worst case separation => separations must be larger => weaker signals => ... I still have some hope that good signal processing might be able to compensate for some of this (ie. integrate several heads' signals under a filter to gain one track's signal). There are some disks that have multiple heads per arm, put my understanding is that each of these heads is independently suspended. -- Andy Glew, andy-glew@uiuc.edu Propaganda: UIUC runs the "ph" nameserver in conjunction with email. You can reach me at many reasonable combinations of my name and nicknames, including: andrew-forsyth-glew@uiuc.edu andy-glew@uiuc.edu sticky-glue@uiuc.edu and a few others. "ph" is a very nice thing which more USEnet sites should use. UIUC has ph wired into email and whois (-h garcon.cso.uiuc.edu). The nameserver and full documentation are available for anonymous ftp from uxc.cso.uiuc.edu, in the net/qi subdirectory.
njk@diku.dk (Niels J|rgen Kruse) (07/31/90)
lindsay@MATHOM.GANDALF.CS.CMU.EDU (Donald Lindsay) writes: >Specifically, it would be nice if we scanned a laser beam over the >media, rather than rotated the media. Or, at least, did the "head" >movement that way. There was hope for this sort of thing, a decade >ago, and somehow it never happened. I believe that the best spatial >modulators had very limited angular effect (...) Would you care to elaborate on this? What kind of spatial modulators? A small mirror mounted on piezoelectric crystal perhaps? A mirror mounted like this has been controlled at up to 1 Khz, i believe (used in a laser sculpture, drawing moving figures with a laser beam). A seektime of a few milliseconds doesn't sound too bad. Even if the angular effect is small, wouldn't it be a simple matter to increase it with some sort of lens arrangement? -- Niels J|rgen Kruse DIKU Graduate njk@diku.dk
jbracher@weber.ucsd.edu (Matt Kennel) (07/31/90)
In article <AGLEW.90Jul30145243@oberon.crhc.uiuc.edu> aglew@oberon.crhc.uiuc.edu (Andy Glew) writes: > >>Which reminds me, what ever happened to the idea of a "head stick", >>i.e. many thin-film magnetic heads, fabricated onto a rigid bar? I >>realize that head yields were awful at one time, and I realize that >>disks used to be great big things. But now, surely, it's time to >>think of tiny little head-per-track disks. > >I periodically ask disk engineer types about this. Usually the answer >comes back "aeronautics". You mean disk drives are not evacuated? Wow, you learn something new every day. Come to think of it, why not? I should think that it would be nice to be able to position the head without worrying about such ugly things as the viscocity of air and its pressure & temperature and the roughness of the platter. Fluid mechanics is exceedingly tough so why bother when you don't have to? >-- >Andy Glew, andy-glew@uiuc.edu Matt Kennel mbk@inls1.ucsd.edu
lindsay@MATHOM.GANDALF.CS.CMU.EDU (Donald Lindsay) (07/31/90)
In article <1990Jul30.231835.13898@diku.dk> njk@diku.dk (Niels J|rgen Kruse) writes: >>Specifically, it would be nice if we scanned a laser beam over the >>media, rather than rotated the media. Or, at least, did the "head" >>movement that way. There was hope for this sort of thing, a decade >>ago, and somehow it never happened. I believe that the best spatial >>modulators had very limited angular effect (...) >Would you care to elaborate on this? What kind of spatial modulators? >Even if the angular effect is small, wouldn't it be a simple >matter to increase it with some sort of lens arrangement? It used to be that one scanned a laser beam by pointing a fixed beam at a rotating mirror - this was the technology inside laser printers. Supermarket barcode readers used a rotating film, with a hologram printed on it. There used to be a lot of hope that we would find less mechanical solutions. I'm out of date on this subject - I stopped reading Laser Focus &c - but I'm not aware of a relevant breakthrough. I think that the problem with limited angular effects was also the limited angular resolution: that is, not enough bits in the seekable address space. If that's still true, then lens arrangements only fix the less-important limitation. Correction are welcome. Does anyone know how the latest laser printers work? -- Don D.C.Lindsay
henry@zoo.toronto.edu (Henry Spencer) (08/01/90)
In article <2684@network.ucsd.edu> mbk@inls1.ucsd.edu (Matt Kennel) writes: >You mean disk drives are not evacuated? ... >Come to think of it, why not? I should think that it would be nice to >be able to position the head without worrying about such ugly things as the >viscocity of air and its pressure & temperature and the roughness of the >platter.... How, exactly, do you keep the head one zillionth of an inch above the disk surface, *without* touching it, in a vacuum? The precision vertical positioning of the head is done "for free" by the air cushion between it and the disk. Doing it mechanically is much harder. -- The 486 is to a modern CPU as a Jules | Henry Spencer at U of Toronto Zoology Verne reprint is to a modern SF novel. | henry@zoo.toronto.edu utzoo!henry
dietz@cs.rochester.edu (Paul Dietz) (08/01/90)
In article <1990Jul31.183218.20342@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >How, exactly, do you keep the head one zillionth of an inch above the disk >surface, *without* touching it, in a vacuum? Magnetic levitation? :-) Paul F. Dietz dietz@cs.rochester.edu
usenet@nlm.nih.gov (usenet news poster) (08/01/90)
In article <2684@network.ucsd.edu> mbk@inls1.ucsd.edu (Matt Kennel) writes: >You mean disk drives are not evacuated? >Wow, you learn something new every day. > >Come to think of it, why not? I should think that it would be nice to >be able to position the head without worrying about such ugly things as the >viscocity of air and its pressure & temperature and the roughness of the >platter. Fluid mechanics is exceedingly tough so why bother when you >don't have to? The key to Winchester and subsequent disks is use of aerodynamics to "fly" the head at a controlled height maintained by the fluid dynamics. No air -> no fluid dynamics -> head crash. While on the subject, why do disks spin so slowly? At 3600 RPM, you have an intrinsic delay of up to 16 msec waiting for the platter to come around, no matter how fast the heads move. You could increase the speed of a 5 1/4" disk by an order of magnitude without worrying about g forces. Aerodynamic heating becomes a problem at higher velocities, but you don't hit the speed of sound until ~120,000 RPM. >Matt Kennel David States
colin@array.UUCP (Colin Plumb) (08/01/90)
In article <2684@network.ucsd.edu> mbk@inls1.ucsd.edu (Matt Kennel) writes: > You mean disk drives are not evacuated? > Wow, you learn something new every day. > > Come to think of it, why not? I should think that it would be nice to > be able to position the head without worrying about such ugly things as the > viscocity of air and its pressure & temperature and the roughness of the > platter. Fluid mechanics is exceedingly tough so why bother when you > don't have to? Because I'm not very keen on building a servomechanism that will track a wiggling, vibration-prone drive platter to within a few millionths of an inch. It's much easier to use an atmosphere and let aerodynamics hold the head at the right altitude, even if the computations aren't entirely trivial. -- -Colin
aglew@oberon.crhc.uiuc.edu (Andy Glew) (08/01/90)
>How, exactly, do you keep the head one zillionth of an inch above the disk >surface, *without* touching it, in a vacuum? How about magnetic suspension? But that would get in the way of the recording, wouldn't it? (Several magnetic suspension techniques might be able to do the trick: superconductive pinning (remember the demos of the high temperature superconductors), the effect (I forget the name) whereby moving a magnet rapidly across a conductive sheet creates a repulsive "image" of the magnet in the sheet) I know disk heads do not fly in vacuum... but thought there were some possibilities here. -- Andy Glew, andy-glew@uiuc.edu Propaganda: UIUC runs the "ph" nameserver in conjunction with email. You can reach me at many reasonable combinations of my name and nicknames, including: andrew-forsyth-glew@uiuc.edu andy-glew@uiuc.edu sticky-glue@uiuc.edu and a few others. "ph" is a very nice thing which more USEnet sites should use. UIUC has ph wired into email and whois (-h garcon.cso.uiuc.edu). The nameserver and full documentation are available for anonymous ftp from uxc.cso.uiuc.edu, in the net/qi subdirectory.
dhinds@portia.Stanford.EDU (David Hinds) (08/01/90)
In article <1990Jul31.200043.5189@nlm.nih.gov> states@tech.NLM.NIH.GOV (David States) writes: >While on the subject, why do disks spin so slowly? At 3600 RPM, you >have an intrinsic delay of up to 16 msec waiting for the platter to >come around, no matter how fast the heads move. You could increase the >speed of a 5 1/4" disk by an order of magnitude without worrying about >g forces. Aerodynamic heating becomes a problem at higher velocities, >but you don't hit the speed of sound until ~120,000 RPM. As far as the disk head is concerned, wouldn't increasing RPM's be the same as increasing recording density? So, for a given speed of drive electronics, you can either push density or RPM's. Either gives you a higher transfer rate. Pushing density gives you a higher capacity, while pushing RPM's gives you a higher random access speed. Sector slewing can practically eliminate the rotational delay for sequential access. So, if you are designing for sequential access speed, it is best to maximize density and leave RPM's alone, until you reach the limiting density of the recording medium. Some drives do spin at different speeds. I think I saw somewhere that IBM is putting 5400 RPM drives in its RS6000 machines. And my PC has an 80MB drive that is essentially a 40MB drive spinning at 2700 RPM and using RLL encoding to achieve the higher density. -David Hinds dhinds@popserver.stanford.edu
elm@sprite.Berkeley.EDU (ethan miller) (08/01/90)
In article <1990Jul31.233407.11825@portia.Stanford.EDU>, dhinds@portia.Stanford.EDU (David Hinds) writes: |> Some drives do spin at different speeds. I think I saw somewhere that |> IBM is putting 5400 RPM drives in its RS6000 machines. And my PC has an |> 80MB drive that is essentially a 40MB drive spinning at 2700 RPM and using |> RLL encoding to achieve the higher density. Yes, IBM's new Lightning drives do spin faster than 3600 RPM. They are 3.5" drives that spin at 4300+ RPM. They're the drives in the RS6000s. ethan ================================= ethan miller--cs grad student elm@sprite.berkeley.edu #include <std/disclaimer.h> {...}!ucbvax!sprite!elm Witty signature line condemned due to major quake damage.
mo@messy.bellcore.com (Michael O'Dell) (08/01/90)
the newest CDC drives (Imprimis come Seagate) spin at 5400 rpm and position noticably faster. good for almost a 50% throughput increase on random traffic....
peter@ficc.ferranti.com (Peter da Silva) (08/01/90)
In article <1990Jul31.194559.4245@cs.rochester.edu> dietz@banana.cs.rochester.edu (Paul Dietz) writes: > In article <1990Jul31.183218.20342@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: > >How, exactly, do you keep the head one zillionth of an inch above the disk > >surface, *without* touching it, in a vacuum? > Magnetic levitation? :-) That might actually be a good idea... for an optical disk. (is that a british zillion or an american zillion?) -- Peter da Silva. `-_-' +1 713 274 5180. 'U` <peter@ficc.ferranti.com>
lindsay@MATHOM.GANDALF.CS.CMU.EDU (Donald Lindsay) (08/01/90)
>In article <1990Jul31.200043.5189@nlm.nih.gov> states@tech.NLM.NIH.GOV (David States) writes: >Aerodynamic heating becomes a problem at higher velocities, >but you don't hit the speed of sound until ~120,000 RPM. With aluminum platters, the upper limit for RPM is set by the fact that high centrifugal forces are bad for the platter lifetime. I suppose we could switch materials, but as David Hinds just pointed out, higher RPM makes it harder to get higher bits/inch. Of course, we could always cool the platters (-: [It's been done! Cub scout's honor! Check out the IBM JR&D in, ahhh, the very early seventies. They built a R/W optical disk that [only] worked at cryogenic temperatures. The article had scope traces, and like that.] -- Don D.C.Lindsay
sysmgr@KING.ENG.UMD.EDU (Doug Mohney) (08/01/90)
In article <10065@pt.cs.cmu.edu>, lindsay@MATHOM.GANDALF.CS.CMU.EDU (Donald Lindsay) writes: >With aluminum platters, the upper limit for RPM is set by the fact >that high centrifugal forces are bad for the platter lifetime. I >suppose we could switch materials, but as David Hinds just pointed >out, higher RPM makes it harder to get higher bits/inch. Aluminum is out, glass (yes, glass) covered with something or another was in. Better data density and cheaper medium, or something like that.
davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr) (08/02/90)
In article <2684@network.ucsd.edu> mbk@inls1.ucsd.edu (Matt Kennel) writes: | You mean disk drives are not evacuated? | Wow, you learn something new every day. | | Come to think of it, why not? I should think that it would be nice to | be able to position the head without worrying about such ugly things as the | viscocity of air and its pressure & temperature and the roughness of the | platter. Fluid mechanics is exceedingly tough so why bother when you | don't have to? The whole technology of hard disks depends on air. That's what keeps the heads from hitting the platters. Without air you would have to have some super accurate means of positioning the heads near the platter. I don't currently see any replacement technology ready to come online. Even the Bernouli based drives use air, but in a slightly diferent way. -- bill davidsen (davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen) "Stupidity, like virtue, is its own reward" -me
pcg@cs.aber.ac.uk (Piercarlo Grandi) (08/02/90)
"lindsay" == Donald Lindsay ??? writes: lindsay> In article <1990Jul30.231835.13898@diku.dk> njk@diku.dk lindsay> (Niels J|rgen Kruse) writes: njk> Specifically, it would be nice if we scanned a laser beam over the njk> media, rather than rotated the media. Or, at least, did the "head" njk> movement that way. The general idea is that the magnetic field is roughly spherical in emission, so you want to keep your head near the surface to cut the smallest most intense intersection with it. Coherent light instead can be focused, even from a great distance. This changes the rule of the game completely, but also causes culture shock to designers (see later). njk> There was hope for this sort of thing, a decade ago, and somehow njk> it never happened. I believe that the best spatial modulators had njk> very limited angular effect (...) I had read that Gary Kildall, The founder of Digital Research, had got into research on very fast CD-ROM readers based on flipping mirrors. Some japanese companies are also doing research on this. njk> Would you care to elaborate on this? What kind of spatial modulators? njk> Even if the angular effect is small, wouldn't it be a simple njk> matter to increase it with some sort of lens arrangement? lindsay> It used to be that one scanned a laser beam by pointing a fixed beam lindsay> at a rotating mirror - this was the technology inside laser printers. lindsay> Supermarket barcode readers used a rotating film, with a hologram lindsay> printed on it. I think that there are several technologies that can be used: Use a traditional positioning arm, but a very low mass one with a lightguide on it. Current optical drives often have the laser diode and a mirror on the head itself. I have read agument for keeping everything close to the surface, but they sound bizarre to me. A laser printer type system, with a rotating mirror for horizontal scanning and a rotating drum for vertical scanning. we have 800x400 DPI printers around, wih a paper surface of say 8.5x11 inches. This gives us around 100 inches of surface, at around 300Kb per square inch, for 30Mbit of storage, i.e. around 4 MBytes. Probably this can be improved by a factor of 100 easily. A system of piezoelectric crystals with mirrored surfaces, scanning at some dozen KHz. Current optical disc drives have an oscillating mirror on the head to cover quickly a band of tracks. A piezoelectric mirror coated crystal could do. Magnetically suspended mirrors with very low mass. IBM built a single chip magnetically operatated mirror on a chip, using sophisticated etching, suspended on two torsion bars of silicon. Its control electronics were around it on the chip. Limited deflection angle, but apparently good enough for laser printers (the intended application). Frequency can be pretty high. Fabry-Perot ineterferometers used not only to modulate, but also to encode the signal. Scanning and encoding frequencies on the order of the GHz range easily accessible (with attendant recording densities). Use of focusing holograms is a variant on the theme. Hologram like recording techniques. Long a dream; three dimensional, extreme density. There have been recent advances, mostly about pattern matching on a fairly gross scale, but also apparently somebody has found ways to use a three dimensional hologram as a storage device. lindsay> I think that the problem with limited angular effects was also lindsay> the limited angular resolution: that is, not enough bits in the lindsay> seekable address space. If that's still true, then lens lindsay> arrangements only fix the less-important limitation. This cannot be. The limited deflection is not a big problem; you can get deflection angles of 2.5 degrees, and these are enough. If you are good at optics, and have money, you can go far. You can focus very precisely from a couple yards away, and a couple yards away can mean enough surface covered at the densities you aim for. I think that there are two problems, one hard and technological, and the other harder and sociological: Limited bandwidth of recording material Reading from an optical medium requires very fast laser modulation. This is not terribly hard. What is hard is to find a recording material tha can change state very quickly, and with low power, and that does not forget the change of state that quickly. If you Have very fast scanning you can refresh, but other problems ensue. The technology requires optics prowess Most all the current mass storage designers are EE engineers, not physicists. In designing an optical scanning system you need high competence in optics. People with this competence do exists, but they don't work for mass storage companies. There is also the problem that really high quality laser optics seems to hinge on advances in phase conjugated mirrors, and those are slow to come. Another problem may be that advanced optics research, especially laser optics, is almost all military funded and very classified. If high bandwidth optical systems come of age, computer centres had better reinforce floors: granite cabinets will become common (like in a prototype IBM 370 with an optics backplane of years ago). -- Piercarlo "Peter" Grandi | ARPA: pcg%cs.aber.ac.uk@nsfnet-relay.ac.uk Dept of CS, UCW Aberystwyth | UUCP: ...!mcsun!ukc!aber-cs!pcg Penglais, Aberystwyth SY23 3BZ, UK | INET: pcg@cs.aber.ac.uk
andrew@alice.UUCP (Andrew Hume) (08/03/90)
to expand on o'dell's note; the imprimis wren runner 2 is a wren 7 spinning 50% faster (3600->5400 rpm) and using 2/3 the cylinders for faster seek times. the forthcoming (that is to say, available now as prototypes) elite 5.25in drives spoin at 5400 rpm as well.
davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr) (08/03/90)
One of the interesting control problems with moving parts of an optical system is that the displacement of a flat plane optical part, lens or laser, is not linear with the movement of the edge. A movement of, say, one micron at the edge may translate into 5 microsec of arc for the first micron, but something else for the next micro. Then if the mirror or laser is looking at a flat plane, the displacement on the plane caused by a microsec of angular displacement is not constant either. Don't quit, diagram follows: || || ||<--------------------------- actuator (vertical move) || ================o <------------- optical device and pivot : (such as lens, laser, mirror) : : : : <--------------------- "line of sight" to the active : area on the media : : _________________________________________________________ ^ |_____ media While the mapping of voltage to actuator position is close enough to linear for the active range, the mapping of actuator movement to postion on the media is highly non-linear. A possible solution to this is to make an actuator which produces constant mapping on movement to angular movement, then use a curved media. This would make the control problems a lot simpler, at the expense of adding a bunch of form factor problems. Blue sky idea: use a cylinder for media, with a bar of mirrors down the axis, and a laser at the end. Side view: ---------------- ================ <== ---------------- To access any area on the cylinder, the correct mirror is raised by activating the pizzoelectric activator under it. Thus seek time is minimal. The laser then illuminates the surface as the cylinder rotates, and the light bounces back to a sensor near the laser. As the diameter of the cylinder increases, the area (capacity) and surface speed (transfer rate) increase. Latency would be proportional to the rpm of the media, and I see no particular reason why it couldn't be removable. Anyway that's my though for the today on the better media. -- bill davidsen (davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen) "Stupidity, like virtue, is its own reward" -me
andrew@alice.UUCP (Andrew Hume) (08/04/90)
In article <11124@alice.UUCP>, andrew@alice.UUCP (Andrew Hume) writes:
~
~
~ to expand on o'dell's note; the imprimis wren runner 2
~ is a wren 7 spinning 50% faster (3600->5400 rpm) and using
~ 2/3 the cylinders for faster seek times.
~
~ the forthcoming (that is to say, available now as prototypes)
~ elite 5.25in drives spoin at 5400 rpm as well.
i should have said the wren runner 2's spin at 4800 rpm.
the elite's spin at 5400 rpm.peter@ficc.ferranti.com (Peter da Silva) (08/04/90)
In article <2386@crdos1.crd.ge.COM> davidsen@crdos1.crd.ge.com (bill davidsen) writes: > Blue sky idea: use a cylinder for media, with a bar of mirrors down > the axis, and a laser at the end. Manufacturing costs for non-flat media are pretty much out of the question. Remember drums? Remember old Edison cylindrical records? -- Peter da Silva. `-_-' +1 713 274 5180. 'U` <peter@ficc.ferranti.com>
tomw@orac.esd.sgi.com (Tom Weinstein) (08/07/90)
In article <10055@pt.cs.cmu.edu>, lindsay@MATHOM.GANDALF.CS.CMU.EDU (Donald Lindsay) writes: > It used to be that one scanned a laser beam by pointing a fixed beam > at a rotating mirror - this was the technology inside laser printers. > Supermarket barcode readers used a rotating film, with a hologram > printed on it. > There used to be a lot of hope that we would find less mechanical > solutions. I'm out of date on this subject - I stopped reading Laser > Focus &c - but I'm not aware of a relevant breakthrough. I think > that the problem with limited angular effects was also the limited > angular resolution: that is, not enough bits in the seekable address > space. If that's still true, then lens arrangements only fix the > less-important limitation. > Correction are welcome. Does anyone know how the latest laser > printers work? > -- > Don D.C.Lindsay I read a paper a couple months ago about something they are doing at NASA. They have a whole series of electrode fingers over a strip electro-optical medium. The fingers are oriented at 45 degrees to the axis of the strip. By applying a potential difference between some of the electrodes and an anode on the other side, they can cause the medium to reflect. Like a dielectric mirror, it's because of the spacing of layers of different indices of refraction. You can get quite good resolution this way. The application they were developing for was laser printers, so they fed it through a diverging lens to convert the spatial displacement to angular displacement. It sounds like this technique could be used for disk drives too. Don't expect this out in printers any time soon, though. They still have a patent application pending last I heard. -- Tom Weinstein Silicon Graphics, Inc., Entry Systems Division, Window Systems tomw@orac.esd.sgi.com Any opinions expressed above are mine, not sgi's.
olson@anchor.esd.sgi.com (Dave Olson) (08/07/90)
In <11137@alice.UUCP> andrew@alice.UUCP (Andrew Hume) writes: | In article <11124@alice.UUCP>, andrew@alice.UUCP (Andrew Hume) writes: | ~ | ~ | ~ to expand on o'dell's note; the imprimis wren runner 2 | ~ is a wren 7 spinning 50% faster (3600->5400 rpm) and using | ~ 2/3 the cylinders for faster seek times. | ~ | ~ the forthcoming (that is to say, available now as prototypes) | ~ elite 5.25in drives spoin at 5400 rpm as well. | | i should have said the wren runner 2's spin at 4800 rpm. | the elite's spin at 5400 rpm. Also note that (unless things have changed recently) the Elite will be out of form factor (about 2 inches longer than a 'standard' 5 1/4" drive. There are also several 3 1/2" drives in the works spinning faster than 3600 RPM. At least one of them has higher sustainable throughput at 16K and 32K i/o sizes than the WrenRunner II (now officially known as the Seagate 4767N). -- Dave Olson Life would be so much easier if we could just look at the source code.
lyndon@cs.athabascau.ca (Lyndon Nerenberg) (08/11/90)
olson@anchor.esd.sgi.com (Dave Olson) writes: >Also note that (unless things have changed recently) the Elite >will be out of form factor (about 2 inches longer than a >'standard' 5 1/4" drive. How recent is your information? I was talking to several suppliers last week about these drives and they indicated the Elite would drop into a standard Sun 5-1/4" disk enclosure (ie shoebox, internal mount in a 3/160, etc). Everyone I talked to expected evaluation units within the next 3 - 4 weeks. Maybe they're in for a bit of a surprise :-) -- Lyndon Nerenberg VE6BBM / Computing Services / Athabasca University {alberta,cbmvax,mips}!atha!lyndon || lyndon@cs.athabascau.ca Practice Safe Government Use Kingdoms