Can one read/write MS-DOS format disks under OS-9?
Yes, there are several public domain and commercially avaliable utilities to accomplish this task, for both OS-9/6809 and OSK. One of the more interesting is the MSFM file manager which appears in OS-9 Insights, a book by Peter Dibble, available through Microware. MSFM is an actual file manager, which allows you to mount an MS-DOS floppy as part of the OS-9 file system. PCF, available from Microware, is an updated file manager which also reads and writes MS-DOS format disks.