On Wed, Oct 21, 2020 at 10:39 AM <silverdr_at_wfmh.org.pl> wrote: > > > > > On 2020-10-21, at 09:06, Francesco Messineo <francesco.messineo_at_gmail.com> wrote: > > > >>>>> Does anyone has been able to transfer Commodore C900 disks to a 5.25" double > >>>>> density, double track disk? > >>>> > >>>> What do you mean by "transfer the disks"? Do you mean using DSDD disks > >>>> instead if DSQD in the C900 floppy drive? it is possible just like with > >>>> the 8250, most DSDD disks can be formatted but they won't be very reliable. > >>> > >>> Never had a problem with using DSDD in a 8050 drive which is a 8250 with > >>> only a single head. > > > > there's no "QD" magnetic media, SD/DD/QD magnetic media was always the > > same (300 oersted). > > Right, but AFAIU that's not the point > > > Probably the diskettes sold as QD/96 tpi were just higher quality. > > Delivering higher resolution without changing the magnetisation characteristics. Similar to "Type I" in analogue audio tapes. One used the same oersteds/bias/eq for different tapes of the same "Type I" but the results could be _hugely_ different between different tapes. in the case of floppy disk drives, it was a better (smaller) head design and a much better head positioning stepper and mechanics. The design of 96tpi and 100tpi drives started by using the old available magnetic media. Then after that, floppy disk manufacturers thought they would make more money if they advertised their standard media as "QD" and 96tpi certified. As they already did the same then MFM and double density was introduced, with always the same magnetic media that was used with FM modulation (called single density). I still have boxes of very old floppies sold as single density. I would not compare analog cassettes to floppy disks. FrankReceived on 2020-10-21 11:00:22
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