> On Dec 30, 2014, at 4:56 PM, Bob Devries <devries.bob at gmail.com> wrote: > > Allen, > > As far as I remember, OS-9 interleaves tracks. > Actually, a "track" on a double-sided disk is 2 x number of sectors per track as defined in LSN0. Meaning to OS-9, a double sided disk is seen as Track 1-40, each containing sectors 1-36??? -- Allen