DFS 0.90 - 8271 BBC B
DFS 0.98 - 8271 BBC B
DFS 2.10 - 1770 BBC B/B+
DFS 2.20 - 1770 BBC B/B+
DFS 2.22 - 1770 BBC B/B+
DFS 2.23 - 1770 BBC B/B+
DFS 2.24 - Master MOS 3.20  But why not a major version change?
DFS 2.25 - 1770 BBC B/B+
DFS 2.26 - 1770 BBC B/B+ Last for the B/B+. Why another B/B+ release after the Master?
DFS 2.45 - Master MOS 3.50  Why the big version jump?

BBC B/B+ 1770 DFS Versions

The first release was 2.0j which was DFS in EPROM. Following this was v2.1 which is 2.0j in ROM.
The release of the BBC B+ 128 saw version 2.2 DFS released.
v2.00
v2.10   Bug in workspace claiming
v2.20   Shift-Z Break function included to emulate the 8271
        Extra commands necessary to deal with the 64K of paged RAM in the B+
v2.21   No record of it's release or existence.

v2.22   Developed to fix an esoteric OSFILE bug.
        Also the 128K associated SRAM utilities have been tidied up to
        make them more user friendly.
        This version will not work in all BBC model Bs fitted with a 1770 upgrade board.
v2.23   Cures the problem of v2.22 not working in all BBCs.
v2.25
v2.26

Master 128 1770 DFS Versions 2.20, 2.24, 2.25, 2.26, 2.27, 2.28, 2.29

v2.20   First Release
v2.24   Supplied in the Master MOS 3.20 System ROM
        Loading with OSFILE &FF returns A=1
        File saves>64K work
        Bugs:
        OSWORD &7F double-density select in drive.b3 does not work
        CLOSE#0 may not leave files with correct length
        CLOSE#0 does not ask MOS to close EXEC/SPOOL
        EXT#= not supported (?)
        Running from DFS as LIBFS does not work correctly
v2.24+  Patched to fix OSWORD &7F double density bug
v2.25   CLOSE#0 and *CLOSE and *SHUT leaves files with correct length
        EXT#= works correctly
        Unknown command as LIBFS works correctly
        Bugs:
        OSWORD &7F double-density select in drive.b3 does not work
v2.26   OSGBPB speeded up
        All four head step rates implemented i.e.
        *CONFIGURE FDRIVE       0       1       2       3
        for 1770                6       12      20      30 mS
        for 1772                6       12      2       3  mS
        Bugs:
        OSGBPB Tube transfers don't work
        OSWORD &7F double-density select in drive.b3 does not work
v2.27/8 Software patch for spurious Motor-on after 1770 reset
        Following fixed:
        If a) A file was open
           b) the disk had been changed
           c) BREAK was pressed
        then the old disk catalogue would be written to the new disk.
        Bugs:
        OSWORD &7F double-density select in drive.b3 does not work
v2.29   OSGBPB Tube problem introduced at 2.26 fixed
        *CONFIGURE FDRIVE 2 has software delay added to hardware delay.
        This allows for support of slow step rate drives with 1772
        fitted, ie
        *CONFIGURE FDRIVE       0       1       2       3
        for 1770                6       12      50      30 mS
        for 1772                6       12      32      3  mS
        Bugs:
        OSWORD &7F double-density select in drive.b3 does not work
v2.29+  Patched to fix OSWORD &7F double density bug

v2.45   Supplied in Master MOS 3.50 System ROM
        ADFS in <thisrom>EOR4 calls DFS floppy access code directly