Here's a silly question, but one I've never understood: Why can't a high density 5 1/4" disk be formatted in a double density drive? When I try, DOS returns a "Track 0 Bad" error message. I thought that a HD disk would simply have a denser coating of magnetic material applied evenly over the entire surface of the disk. I don't see why this should cause problems for a DD drive. However, a few questions come to mind. Is the magnetic coating of a different sensitivity, resulting in a weaker signal for the heads to pick up? Is the magnetic coating applied to the media in "tracks", causing problems when a different TPI spec is attempted on the disk? Since some of the software for my "old" (first generation PC) computers is on 5 1/4" disks of dubious condition, I would like to make copies onto new disks. Since HD disks are still readily available and cheap, I thought this would be an ideal way to do so. I also seem to have fried the 5 1/4" HD drive in my PC while sorting through some old software. It seems a couple of disks had some dirt on them which caused horrible screeching sounds when the disk was spinning, and also deposited a very hard black coating on the heads. The only way I could remove the deposits was to scratch it off with my fingernails (alcohol would not touch it). However, I must have bumped the heads out of alignment, because the drive won't read disks any longer. My question is: can I plug a Double Density drive into the same connector in my modern PC and use it for my old disks? I know I will have to change my BIOS setting, but is there anything else I need to consider? Any input on the above would be much appreciated... thanks in advance! Hope this isn't too far off topic. Grant Zozman gzozman(a)escape.ca