> -----Original Message----- > From: tclug-list-bounces at mn-linux.org [mailto:tclug-list-bounces at mn-linux.org]On Behalf Of Mike Miller > Sent: Sunday, July 27, 2008 1:58 PM > To: TCLUG List > Subject: [tclug-list] longevity of floppy disks > > > On Sun, 27 Jul 2008, Josh Paetzel wrote: > > > The chances that the floppies themselves are actually any good are > > fairly low. Back in the mid 90's in the midst of a move I checked all > > the 5.25" floppies I had, as at that point it had been years since I > > used them, and the vast majority of them had errors. My guess is that > > unless these were very recently written there's probably no usable data > > left on them. Depends on such things as media quality (ie, some function of “coercivity” in the magnetic coating, plus the recording “energydetails”)... some last, some are easily recoverable, and some aren’t. Adjacent magnetic domains influence each other and are likely to smear to nothing in time. Lower temps can extend that,and some combos change very slowly. Hard drives will do this also, but the many layers of “smarts” in modern drives that do error checking and re-writing are likely to hide what really happens, and extend data life greatly... if power is on often enough. > I wasn't the original poster on this one, but... > > I'm surprised to hear that these disks are expected to fail at this point. > I guess it has been 20 years since I looked at some of my old disks but I > was thinking I could copy some of the files off of them, copy them to my > HDD and toss the disks in the trash. > > They really don't last this long if kept in a cool dry place, in their > sleeve in one of those old disk cases? Might be a crap shoot. It’s a combo of media qualities plus recording signal “energy” details. No simple way to check anything, except to try to copy to a hard disk, then to a CD. My old floppies are usually readable and/or recoverable. Some of mine go back as far as 5.25 inch media can... c1980? > I thought they would last longer. I have watched some VHS tapes made 20 > years ago and they still work fine -- not digital, but they are magnetic > media. It is in fact an analog waveform on the media, and the biphase-like “signal waveform” can fade. Blurring to increase the inter-symbol interference is the most common kind of error, but some old media actually have the oxide flake off. CRC by sector and other “clumpings” helps detect and recover errors (when enough oxide stays stuck on). I think punched cards may be the only truly digital media we’ve had. Chuck