john@wa3wbu.UUCP (12/05/87)
I realize this has probably been hashed out before but I have been asked this so many times recently I just must ask it myself: Why don't HD (1.2MB) floppy diskettes have hub reinforcment rings like the 360K ones do ? I have disks around here from about 6 or so different vendors and notice the same on all. Thanks. John, WA3WBU -- John Gayman, WA3WBU | UUCP: uunet!wa3wbu!john 1869 Valley Rd. | ARPA: wa3wbu!john@uunet.UU.NET Marysville, PA 17053 | Packet: WA3WBU @ AK3P
indra@amdcad.AMD.COM (Indra Singhal) (12/07/87)
In article <415@wa3wbu.UUCP> john@wa3wbu.UUCP (John Gayman) writes: > > Why don't HD (1.2MB) floppy diskettes have hub reinforcment rings >like the 360K ones do ?.... I would think one reason could be the need to distinguish one from the other !! If both HD and 360K floppies had hub rings we would not know one from the other ! -- -I said so... & said it for myself. Indra K. Singhal {ucbvax,decwrl,allegra}!amdcad!indra or amdcad!indra@decwrl.dec.com
howardl@wb3ffv.UUCP (Howard Leadmon ) (12/08/87)
In article <415@wa3wbu.UUCP>, john@wa3wbu.UUCP (John Gayman) writes: > > Why don't HD (1.2MB) floppy diskettes have hub reinforcment rings > like the 360K ones do ? I have disks around here from about 6 or so > different vendors and notice the same on all. Thanks. > > John, WA3WBU Hello John, Now that is a good question, I would really like to know that myself!! I too have bought disks from several different manufactures (in an attempt to get some with hub rings), but as of this date I have never been able to any high-density disks with hub rings. So if anybody has the answer to this rather unusual question, please post it to this group... Sincearly, Howard Leadmon (WB3FFV) cp1!sarin!wb3ffv!howardl (301)-335-2206
WS5@PSUVM.BITNET (12/17/87)
alignment is much more critical than for standard floppies, and it seems
that the reinforcing ring tends to cause head tracking problems with these
disks, so the manufacturers don't use the ring on the disks.
I read that explanation somewhere a while back, and unfortunately don't
remember where. Anyway, it seems plausible to me.
dorin@batcomputer.tn.cornell.edu (Stewart Johnson) (12/17/87)
This is my first attempt at posting, forgive me if I mess it up. Here's my guess: The old full-height black faced ibm floppy drive has a hub engagement mechanism that is a real monster masher. Bad design. Even with hub reinforcement rings it has tweeked alot of precious floppies. Later models, such as the half-height HD models, have a much smoother hub engagement mechanism, thereby (supposedly) eliminating the need for a reinforcement ring. I could be wrong. Now I have a question: I know that hard drives use heavy energy and give off bunches of heat. But WHERE do they give off the heat FROM, the disk unit or the controller? I would guess it is the disk unit, but if so then WHY on all the PC/XT's is the hard drive on the right where it will experience less efficient cooling? dorin@mathvax.msi.cornell.edu Stewart Johnson "Back Off--I'm a Scientist" P.O. Box 492 Ithaca,N.Y. 14851
cm450s02@uhccux.UUCP (Jeff T. Segawa) (12/18/87)
In article <3209@batcomputer.tn.cornell.edu> dorin@tcgould.tn.cornell.edu (Stewart Johnson) writes: > >Here's my guess: The old full-height black faced ibm floppy drive has a hub >engagement mechanism that is a real monster masher. Bad design. Even with >hub reinforcement rings it has tweeked alot of precious floppies. > I didn't catch the beginning of this dicussion, but is anyone trying to use high density floppies in an old 360K drive? (the H.D. floppies I've seen do not use the reinforcing ring). If so, I'm not surprised if you're seeing lot of "Error reading drive A: Abort, Retry, Ignore?" messages. Not only will some of those drives chew up the center of the disk, but I don't think the magnetic media itself can be written to reliably w/anything but a high density drive. I figured this out after a few frustrating hours. >Now I have a question: I know that hard drives use heavy energy and give >off bunches of heat. But WHERE do they give off the heat FROM, the disk unit >or the controller? Can't say for sure in the case of an IBM, but with my Mac II, the entire cast aluminum structure of the Seagate drive gets warm. Can't find any especially hot spot, though. None of the chips on the motherboard (including the SCSI chip) seems to get more than slightly warm, either. I also used to have a SCSI card for IBMs, and I don't recall seeing any of the parts heavily heatsinked, so I'd suspect that the drive itself is the biggest source of heat, at least in SCSI systems.
john@wa3wbu.UUCP (John Gayman) (12/20/87)
In article <3209@batcomputer.tn.cornell.edu>, dorin@batcomputer.tn.cornell.edu (Stewart Johnson) writes: > Here's my guess: The old full-height black faced ibm floppy drive has a hub > engagement mechanism that is a real monster masher. Bad design. Even with I received several replies to my inital question. The biggest opinion seemed to be that the HD floppies have no hub-ring so you can tell them from 360K floppies in bulk form. I'll admit, it'd be pretty hard to tell the difference without trying to format them. I had remembered reading something a while back about the HD drives being sensitive to hub configurations. But then again, you can put 360K floppies in a HD drive to read them and it doenst appear to cause the drive any harm. So I guess I can beleive that it's to tell them apart. Anyone with conflicting stories ? :-) > Now I have a question: I know that hard drives use heavy energy and give > off bunches of heat. But WHERE do they give off the heat FROM, the disk unit The controller gives off a very insignificant amount of heat. The majority of the heat comes from the disk drive itself. If you've ever taken your machine apart after having it run for many hours or a day (XT variety) you'd notice the hard disk drive is *very* warm. This is the reason that its recommended a dual hard disk XT have the drives side-by-side. I beleive it is normal for the hard disk to run warm. I've noticed the same thing on hard disks in mini's and mainframes. They must have adaquate ventilation though. This is also the reason that its important you let a new driver "warm up" a bit before doing a low-level format to allow its temperature to stabilize. Lets face it, the XT doesnt have the greatest cooling system. I used to notice mine getting quite warm on top after several hours operation. I do not notice the same on my AT, the AT has a much better air-flow and stays *much* cooler. TO get back at the original question ( :-)) the heat within the hard disk module comes from the positioning motor and sindle motor. John -- John Gayman, WA3WBU | UUCP: uunet!wa3wbu!john 1869 Valley Rd. | ARPA: wa3wbu!john@uunet.UU.NET Marysville, PA 17053 | Packet: WA3WBU @ AK3P
wtm@neoucom.UUCP (Bill Mayhew) (12/21/87)
The coercivity of the magnetic material on HD floppies is greater than the material used for 360K diskettes. The above fact prevents a 360K drive from writing on them. The situation is analogous to trying to record on a metal cassette tape in a standard tape recorder. Unfortunately, it still doesn't explain why HD disks don't have hub rings!! --Bill
caf@omen.UUCP (Chuck Forsberg WA7KGX) (12/29/87)
:Unfortunately, it still doesn't explain why HD disks don't have hub
:rings!!
:
Every HD drive I have seen has an "anti-scruntch" feature that spins
the hub when a diskette is inserted. This alleviates the need for a
strong (i.e., reinforced) center hole in the diskette.
Two caveats: 1) Make sure the computer is powered up before inserting the
diskette. 2) SLOWLY turn the lever to lock the diskette in the drive,
give it a chance to get up to speed and seat the diskette.
Failure to observe the above cautions has damaged the center hole,
sometimes rendering the diskette unreadable. Scruntching diskettes
is the DOS analogue to Unix rm -rf /.
Chuck Forsberg WA7KGX Author of YMODEM, ZMODEM, Professional-YAM, ZCOMM, and DSZ
...!tektronix!reed!omen!caf Omen Technology Inc "The High Reliability Software"
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P.S.: I have seen a few HD diskettes with hub rings. Conroy-LaPointe
used to sell them.tjfs@otter.hple.hp.com (Tim Steele) (02/16/88)
Well, the *real* reason (according to Inmac) is that the reinforcing ring does indeed disturb the disk alignment slightly (a price worth paying on a low density disk drive that chews floppies), which is not acceptable on HD drives. Tim