>...why do floppies fail? Because the OS doesn't find the information it expects to be there.
Drive trouble: 1. The drive head may be so clogged with lint and magnetic-media debris that it can't read some floppies. Clean it! (I've never seen this to be a problem even though I've blown out copious quantities of dust...with my mouth not a bottle of over-priced air. ;-) I've never used one of the solvent-applying, cleaning disks and have heard that they have the potential to cause other problems.) 2. The drive head alignment has changed since the disk was written such that now it can't achieve the tolerable juxtaposition to read the data. Replace it! (At $10-15 for a used one, the hassle of realignment isn't worth the effort.) Floppy trouble: 1. The thin film of iron-oxide magnetic media which is deposited on both sides of the plastic disk (substrate) ain't there anymore. Inside the floppy case are a couple of fabric pads that wipe the surface of the floppy to remove dust so that it does jam-up the drive heads which read the floppy. If a piece of dirt...a small grain of sand...gets trapped on the pads, it may slowly grind a groove in the floppy media. If it removes enough material, which it can, data will be lost along with the integrity of the registering info. Even if not, those tiny chunks of magnetic media build up on the pads or, worse yet, on the read heads. Being of the same hardness as the rest of the floppy media, they grind away quite effectively. As you can imagine, this problem builds on itself. Unlike the heads in a hard drive which literally fly above the media (platters) on a thin film of air, the heads in a floppy drive are forcibly held against the media exacerbating the deterioration. The OS will permit a limited number of "bad" sectors where the media has been "torn away" on a "good" floppy. It keeps track of where these are and doesn't allow anything to be written to those areas. You may find it educational to examine a stubborn floppy with something like Norton Speed Disk to show the location of bad sectors. You might even notice a telltale pattern in the faulted sectors where media on adjacent tracks has been lost. Given the risk, one bad sector is reason enough to throw out the culprit...it won't get better and is nearly certain to get worse. If the media is damaged on the first few sectors (drums) where the information on file location and bad sectors are stored, the disk is immediately worthless and unformatable. This is usually the first and fatal indication of trouble with a floppy. :-( 2. Temperature gradients due to exposure to heat sources may create permanent local distortion in the plastic media substrate causing physical errors in reading due to the geometry change. 3. Magnetic damage. Data on a floppy can be distroyed by causing or allowing a magnetic field to sweep through the disk such as running a vacuum cleaner or other DC motor too close or bringing a magnetized object near a disk. The result is a large scale analogy of the writing operation of the floppy drive head. The floppy can be reformatted and used unless the outer sectors have been effected as noted above. 4. EMI damage to a floppy? I don't think so. Maybe a high-energy electromagnetic pulse..."Jim, we've been hit. Our cloaking shields are dropping." ;-) 5. Letting your dog chew on them will do it, too. Bob Gray Huntingtown MD [EMAIL PROTECTED] -- PCI-PowerMacs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | -- Sonnet & PowerLogix Upgrades - start at $169 | & CDRWs on Sale! | PowerON Computer Services <http://www.poweron.com> REPLACEMENT PARTS in STOCK Drives, CD-ROMs, RAM, Mac OS SW, Power Supply <mailto:[EMAIL PROTECTED]> Support Low End Mac <http://lowendmac.com/lists/support.html> PCI-PowerMacs list info: <http://lowendmac.com/lists/pci-powermacs.shtml> Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/pci-powermacs%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
