Floppy disks again

I wrote: To which Allison replied: ] ???? Nonsense question, no context. I have no difficulty ] nor is there any reason to expect difficulty with 96tpi DD ] ops. I have expereinced using formerly formatted media of ] 96 or 48TPI that REQUIRED bulk erasure to be usable. I believe ] that intertrack noise due to differnt track widths are why. ] I regurally use PC360k, Vt180, RX50 and Visual1050 media and they ] are 48 TS, 48 SS, 96ss, 96ss/TS all running at DD data rates. ...much more, deleted... Oh yeah, you can't read my mind. Guess I better include some context. I'm thinking of the 5.25" DS/DD floppy disks commonly used in PC's and formatted to hold 360K at 48TPI. I was recently discussing with someone whether or not they could be used as RX50's, which as you know have 96 tracks per inch, with each track having the same number of bits as in the PC 360K DS/DD format. Both are supposed to be 300 Oerstedts. But I think I remember hearing complaints that the not-so-high-quality DS/DD 360K floppy disks would not work okay with the higher number of tracks per inch. And I am sure I read something about the importance of these diskettes being "well honed" to be used as RX50's, with the assertion that not all 360K DS/DD disks are. (But "well honed" was left undefined, and I'd love to know what exactly was meant, as well as what physical property of those not-so-high-quality diskettes was causing them to fail.) Now I'm not talking about writing more on any one track. It might still be just exactly the same as the PC DS/DD format. And coercivity doesn't come into the picture, because we are talking about floppy drives that are made to work with 300 Oerstedt media, which those DS/DD disks are. I'm also not thinking of taking a diskette written by one drive and trying to read it in another. That can cause problems because 48TPI tracks might be twice as wide as those written in a 96TPI drive. Simple enough; no confusion. The point I'm after is about the limitation on how many tracks that disk can hold - does that limitation come from something about the diskette itself, or is it a property of the disk drive in which it is used? My thinking is that the media can handle >3000 magnetic transitions (bits) per inch, because it does that along each track. So that can't be the limiting factor that prevents you from fitting 96 tracks into one inch. I'm not concerned with the drive in which it is written; I only care about what the media could hold if I had a precise enough disk drive. Assuming that the magnetic granules in the oxide are not systematically shaped in any odd way, (not generally longer than they are wide, or wider than long), then the media itself should in principle be able to handle 3000 tracks per inch - just as many transitions moving outward from center as moving along a track. If the diskette itself was so crappy that it couldn't handle 96 magnetic transitions radially, then it should have no hope of being able to handle 3000/inch when writing a track, so it would also have no hope of being usable in the PC 360K 48TPI format. Conversely, if it could handle the 3000 transitions per inch of the PC 360K DS/DD format, then the media itself is already *much* better than necessary to handle 96TPI. So the limitation is in the drive, and not the diskette; and any old never-written (or properly bulk-erased) "PC 360K" diskette should be perfectly happy as an RX50. It just occurred to me that the recorded track must be more or less like a UPC bar code - the width of the track is very much greater than the length of a bit in the track; maybe more than 200 times greater. So say the track was a 1 meter wide sidewalk, the bits would each be 1m wide, but only 5mm long. So even a tiny twist in the read head would gum it up real good - it should be much more sensitive to this than to alignment. Move 1cm to the left, and you are still 99% on the sidewalk - no problem. But twist just one degree, and when your left side is at one bit, your right side is three bits ahead or behind - big trouble. Well, maybe the forces acting on the head are less likely to twist it than to shift it. Bill.