lphillips@lpami.wimsey.bc.ca (Larry Phillips) (03/05/90)
In <3891@nmtsun.nmt.edu>, dksnsr@nmtsun.nmt.edu (Dr. Mosh) writes: > >Different magnetic properties??? I don't think so, most bulk HD disks are >just tested for the maximum storage... They also have an extra hole that >designates them as HD disks... but as far as different magnetic properties... >you'll have to go for maybe the higher priced stuff... Nope. HD diskettes use media that has a different coercivity. The implication of this is that to properly write a HD diskette you need a highr write current. Normal (2S/2D) floppy drives don't have the oomph to write them properly, and depending on the drive, the data may or may not be there, and if it is, may or may not be there an hour or a week from when it's written. -larry -- Gallium Arsenide is the technology of the future; always has been, always will be. +-----------------------------------------------------------------------+ | // Larry Phillips | | \X/ lphillips@lpami.wimsey.bc.ca -or- uunet!van-bc!lpami!lphillips | | COMPUSERVE: 76703,4322 -or- 76703.4322@compuserve.com | +-----------------------------------------------------------------------+
rokicki@Neon.Stanford.EDU (Tomas G. Rokicki) (03/06/90)
Do not use HD floppies in a normal Amiga floppy drive. The HD disks are *different*---different magnetic properties. They will work---to a point. Your data isn't worth it, and the DD are cheaper anyway. -tom
lphillips@lpami.wimsey.bc.ca (Larry Phillips) (03/06/90)
In <90065.140254JAM160@psuvm.psu.edu>, JAM160@psuvm.psu.edu (James MacKenzie) writes: > >Sorry, Tom, but there is NO difference in the magnetic media of HD and DD >3-1/2" disks...in fact, you can take a DD 3-1/2" disk and put a hole in >it where the extra one is on a HD, and it will work. Going that direction is a little more reliable than going the other direction. Tell you what. You buy a HD floppy diskette. Format it on your Amiga. put your normal boot stuff on it. Use it if it holds the data at all. Tell me how long it goes before you have a munged, unusable boot disk. Tell me why. -larry -- Gallium Arsenide is the technology of the future; always has been, always will be. +-----------------------------------------------------------------------+ | // Larry Phillips | | \X/ lphillips@lpami.wimsey.bc.ca -or- uunet!van-bc!lpami!lphillips | | COMPUSERVE: 76703,4322 -or- 76703.4322@compuserve.com | +-----------------------------------------------------------------------+
dksnsr@nmtsun.nmt.edu (Dr. Mosh) (03/06/90)
In article <1990Mar5.205252.28816@Neon.Stanford.EDU> rokicki@Neon.Stanford.EDU (Tomas G. Rokicki) writes: >Do not use HD floppies in a normal Amiga floppy drive. The HD disks are >*different*---different magnetic properties. They will work---to a point. >Your data isn't worth it, and the DD are cheaper anyway. > >-tom Different magnetic properties??? I don't think so, most bulk HD disks are just tested for the maximum storage... They also have an extra hole that designates them as HD disks... but as far as different magnetic properties... you'll have to go for maybe the higher priced stuff... -Dino Khoe dksnsr@nmtsun.nmt.edu
JAM160@psuvm.psu.edu (James MacKenzie) (03/07/90)
In article <1990Mar5.205252.28816@Neon.Stanford.EDU>, rokicki@Neon.Stanford.EDU (Tomas G. Rokicki) says: > >Do not use HD floppies in a normal Amiga floppy drive. The HD disks are >*different*---different magnetic properties. They will work---to a point. >Your data isn't worth it, and the DD are cheaper anyway. > >-tom Sorry, Tom, but there is NO difference in the magnetic media of HD and DD 3-1/2" disks...in fact, you can take a DD 3-1/2" disk and put a hole in it where the extra one is on a HD, and it will work. ------------------------------------------------------------------------------- | James A. MacKenzie jam160@psuvm (.psu.edu) / jam@psuhcx (.psu.edu) | | mckenzie@endor.cs.psu.edu | -------------------------------------------------------------------------------
mmaston@portia.Stanford.EDU (Michael Maston) (03/07/90)
In article <3891@nmtsun.nmt.edu> dksnsr@nmtsun.nmt.edu (Dr. Mosh) writes: > > >Different magnetic properties??? I don't think so, most bulk HD disks are >just tested for the maximum storage... They also have an extra hole that >designates them as HD disks... but as far as different magnetic properties... >you'll have to go for maybe the higher priced stuff... > >-Dino Khoe >dksnsr@nmtsun.nmt.edu I believe that they DO have different properties. Just as the HD in 5.25" disks are different magnetic media. This is necessary to allow the higher density of data in the same physical space. Ever tried to format a low density (360KB) disk to high density capacity (1.2M) on an IBM? All you typically end up getting is a ton of errors and a nearly unusable disk! Mike PS: Besides, as was said before, you can't USE that higher density on an Amiga drive to get more storage, so why pay more to get no more functionality?
hart@ug.cs.dal.ca (Todd Darrell Raymond Hart) (03/07/90)
>>Do not use HD floppies in a normal Amiga floppy drive. The HD disks are >>*different*---different magnetic properties. They will work---to a point. >>Your data isn't worth it, and the DD are cheaper anyway. >>-tom >Different magnetic properties??? I don't think so, most bulk HD disks are >just tested for the maximum storage... They also have an extra hole that >designates them as HD disks... but as far as different magnetic properties... >you'll have to go for maybe the higher priced stuff... >-Dino Khoe My understanding is the same as Dino's, one is just tested to higher standards, there is no real difference INITIALLY. After formatting though, a HD drive creates magnetic patterns that are hard if not impossible to reformat in a DD drive. I have tried to format a 1.44M diskette from a PC in my Amiga, it just gagged starting with the first track (something about unable to create a proper sync mark I seem to remember). Just taking a magnetic bulk eraser to the disk made it perfectly usable (a friend of mine uses DDs with holes drilled in them all the time as HDs with no problems and just bulk erases one whenever he REALLY needs a DD to transfer software to another machine without HD). -Todd Hart Now where did that footer go?!?
dksnsr@nmtsun.nmt.edu (Dino Khoe) (03/07/90)
> >I believe that they DO have different properties. Just as the HD in 5.25" >disks are different magnetic media. This is necessary to allow the higher >density of data in the same physical space. Ever tried to format a low >density (360KB) disk to high density capacity (1.2M) on an IBM? All you >typically end up getting is a ton of errors and a nearly unusable disk! > >Mike Yes, I agree that in essence they do have different magnetic properties... but a lot of bulk disk manufacturers do not heed this, they merely punch the extra hole needed and test the disk for write capabilties, I've never worked with a 5 1/4" so I wouldn't know about those... but for 3 1/2's it's easy to make any DD/DS HD... And plus, they offer Lifetime Warranties because, how much could a single disk cost to replace? -- ============================================================================= Dino Khoe | | | / \ /\ |/ Any system dksnsr@nmtsun.nmt.edu | |---||____|| |\ can be New Mexico Tech Computer Science | | || | \/ | \ cracked...
psu@mtuni.ATT.COM (Paul Siu) (03/07/90)
If you do decide to make a DS/DD disk into a HD by punching a hole, make sure you use one of those special convertor tools they sell in the computer store, or if you are on a budget, a soldering iron (to burn a hole through it). If you try to drill a hole through it, you'll leave pieces of plastic inside your disk, and it will fail. I do not know how reliable DS/DD disk are when they are formated at HDs.
dales@teksce.SCE.TEK.COM (Dale Snell) (03/07/90)
[woof!] In article <3912@nmtsun.nmt.edu> dksnsr@nmtsun.nmt.edu (Dino Khoe) writes: | | ... And plus, they offer Lifetime Warranties because, |how much could a single disk cost to replace? | Just a few cents. But how much would it cost to replace your data? --dds Dale D. Snell dales@teksce.SCE.TEK.COM 74756.666@compuserve.COM "Just a thought... Sand in the wind."
dalka@cbnewsc.ATT.COM (kenneth.j.dalka) (03/07/90)
>>Do not use HD floppies in a normal Amiga floppy drive. The HD disks are >>*different*---different magnetic properties. They will work---to a point. >>Your data isn't worth it, and the DD are cheaper anyway. I have a friend who has a messydos machine. He buys low density 3 1/2 floppies and drills holes in them for use with his machine. He says he has to buy "good quality" disks rather than the $.40 ones which he says he spends about $.85 per disk in lots of 100. Still a LOT cheaper than using the high density. I've also heard that many disk makers only make one kind of disk. They just certify a certain portion for the higher dendity. -- Ken Dalka (Bell Labs) att!ihlpz!dalka IH 4H-416 (312) 979-6930
amiga.chairman@canremote.uucp (AMIGA CHAIRMAN) (03/08/90)
Actually the quad density 3.5" disks do have different magnetic properties. Regards Charles --- * Via ProDoor 3.1R
dca@toylnd.UUCP (David C. Albrecht) (03/08/90)
In article <90065.140254JAM160@psuvm.psu.edu>, JAM160@psuvm.psu.edu (James MacKenzie) writes: > In article <1990Mar5.205252.28816@Neon.Stanford.EDU>, rokicki@Neon.Stanford.EDU > (Tomas G. Rokicki) says: > > > >Do not use HD floppies in a normal Amiga floppy drive. The HD disks are > >*different*---different magnetic properties. They will work---to a point. > >Your data isn't worth it, and the DD are cheaper anyway. > > > Sorry, Tom, but there is NO difference in the magnetic media of HD and DD > 3-1/2" disks...in fact, you can take a DD 3-1/2" disk and put a hole in > it where the extra one is on a HD, and it will work. > Well, that doesn't really prove anything. Having it work and having it work well are two different things. I haven't tried this particular economy myself (though I've seen plenty of ads for hole punchers) but, last I read was that while it would work fairly reliably as long as you use the same drive they tend to be flakey going from one drive to another. If true, this is bad enough behavior to make it an unwise economy in my eyes. I would have nightmares about my current drive going belly up and the replacement being unable to read a significant portion of my disks. David Albrecht
md3b+@andrew.cmu.edu (Matthew Donald Drown) (03/09/90)
I'm not sure about 3.5" disks, but the disks for 5.25" weren't any different that I know of. Before my Amiga I had a venerable C64, because I ran a BBS I bought a SFD 1.2meg drive. The drive would only format cheap disks, I bought a ten pack of high density 5.25" and the drive gave me format errors. I do know that the 3.5" disks have some physical difference, but this sounds like a marketing ploy, no clue. -Matt Drown md3b@andrew.cmu.edu
mwandel@tiger.waterloo.edu (Markus Wandel) (03/09/90)
In article <gZxfIWu00Xc1Q0Pl4R@andrew.cmu.edu> md3b+@andrew.cmu.edu (Matthew Donald Drown) writes: > > I'm not sure about 3.5" disks, but the disks for 5.25" weren't > any different that I know of. Before my Amiga I had a venerable > C64, because I ran a BBS I bought a SFD 1.2meg drive. The drive > would only format cheap disks, I bought a ten pack of high density > 5.25" and the drive gave me format errors. I do know that the > 3.5" disks have some physical difference, but this sounds like a > marketing ploy, no clue. Before everybody starts taking this as evidence that there is no such thing as 5.25" high density disks either, it should be pointed out that the SFD 1001 drive does in fact store a megabyte on regular double density "360K" disks. It uses a double sided, 80 track mechanism (360K drives use 40 track mechanisms), and it uses a variable bit-rate GCR encoding which packs a little more than the usual amount on each track. But it's still a regular "double density" drive, and it uses regular "360K" disks. The high-density disks are a different animal, and the SFD 1001 can't use them for the same reason that most other double density drives can't. Note: "Single Density" --> obsolete FM encoding scheme. "Double Density" --> 250kbps MFM encoding, (i.e. 360K 5.25" disks, the Amiga disks, etc). Also applied to other schemes (like the GCR encoding used by C64s and Macintoshes) when they give similar recording densities. "High Density" --> 500kbps, 360RPM, 1.2 meg floppies in the PC AT, or 500 kbps, 300RPM, 3.5" 1.44 meg floppies "Quad Density" --> a term sometimes applied to higher-than-normal capacity disk systems, such as 80-track drives in the SFD 1001, various CP/M systems, etc. Usually used the same disks as the double density drives. Disclaimer: I don't really know what I'm talking about, so keep the flame throwers on "medium rare" please and just correct any errors. Markus Wandel mwandel@tiger.waterloo.edu (519) 884-9547
amigo@milton.acs.washington.edu (Michael Robertson) (03/10/90)
In article <1205@lpami.wimsey.bc.ca> lphillips@lpami.wimsey.bc.ca (Larry Phillips) writes: >In <90065.140254JAM160@psuvm.psu.edu>, JAM160@psuvm.psu.edu (James MacKenzie) writes: >> >>Sorry, Tom, but there is NO difference in the magnetic media of HD and DD >>3-1/2" disks...in fact, you can take a DD 3-1/2" disk and put a hole in >>it where the extra one is on a HD, and it will work. > >Going that direction is a little more reliable than going the other direction. > >Tell you what. You buy a HD floppy diskette. Format it on your Amiga. put your >normal boot stuff on it. Use it if it holds the data at all. Tell me how long >it goes before you have a munged, unusable boot disk. Tell me why. > I have a few 3.5 HD disks around, found they aren't very usuable in Commodore's stock drives (the internal), but my external which is a Toshiba, treats these as any other 3.5" disk. I have had NO problem with it working on that drive, but like I said, the drives Commodore uses on the internal (Mitsumi or something like that) won't read it AT ALL. I think it has to do with the quality of the mechanisms, and things like how the head reads the disk. Being as the HD disks are actually using a different type of coating - this is similar to the variations in cassette tapes. There's Ferric, Chrome, and Metal cassettes, in the disk world though, they're something different of course. Anyhow, its the variation that causes it to not read right on the internal, the external I figure uses the same head as a HD drive, so therefore it reads/writes just fine.