There were two Osborne floppy formats. Both CP/M.
IIRC, the original format was "Single Density" (FM), 10 sectors per track,
with 256 bytes per sector (similar to the TRS80-Model-1. That will
require FM/SD capability. Most NEC FDCs did not support that. Dave
Dunfield has a test program that will tell you whether your FDC can handle
it.
Then, they switched to "Double Density" (MFM) IIRC: 5 sectors per track,
with 1024 bytes per sector. Any PC FDC with access to INT13h and INT1Eh
will work with appropriate software. (NOT external USB drives)
WITH appropriate software, a flux transition device, such as your
Catweasel, could do it.
On Mon, 24 May 2021, Zane Healy via cctalk wrote:
A photographer I know contacted me last night asking
about reading Osborne 1 floppies. What does it take to read these?
The only Catweasel board I have is the old Zorro 2 board for the Amiga. I do have 5.25?
floppy drives. Neither of us have an Osborne anymore (I think mine went to Jim Willing).
Zane