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> On Sep 8, 2023, at 13:15, Fred Cisin via cctalk <cctalk@classiccmp.org> wrote: > > On Fri, 8 Sep 2023, Anders Nelson via cctalk wrote: >> Hi all, >> I just bought a very clean, DSDD 8" disk drive off eBay and it has a 50p >> connector which I guess is the common Shugart type? I also found a 50p-> >> 34p adaptor PCB design someone documented online. > > very few of the lines need to be rearraanged, so you can just twist a few > wires in a cable. One exception is that if you need the TG43 signal for > writing, then you will need additional circuitry. > >> I haven't delved much into floppy formats (high level or low level) but I'm >> somewhat familiar with filesystems from FAT12. My ultimate goal is to >> create an open-source USB >> adaptor that reads/writes the contents of an 8" >> disk but presents itself to an OS as a Mass Storage Device (block device). >> Is such a thing possible? > > Sure. Ine the very early days of external USB floppies, there existed a rare > few in which the circuitry was a general purpose FDC. All currently produced > ones are locked in to only supporting a couple of PC 3.5" formats. Look for > "mode 3", which is support for the NEC format, which is compatible with 8" > formats, IFF you can modify the hardware to work. > >> I once created a terrible custom format for storing data on a flash chip >> which required no low-level format, but I expect a magnetic disk needs >> headers/trailers to know when a track starts/stops so it can skip around. > > Yes. It is called "IBM format", but that is confusing, since it is talking > about the track structure that IBM designed (3740?), NOT about IBM PC (which > does use that structure) > >> I checked out the KyroFlux website and it seems there are dozens of formats >> that were used for 8" disks - is there a favorite format among the >> community that allows full use of a 1.2MB 8" disk? > > Not everybody will agree, but, . . . > NEC modified their 3.5" drives to be 360RPM, same as their 5.25" 1.2M drives, > and 8" drives. Thus, they used the same format on all three sizes! > > http://www.xenosoft.com/fmts.html#8 > > > -- > Grumpy Ol' Fred ci...@xenosoft.com
