1581 & subdirs

Floppy drive 1581 doesn't have "subdirs", it have partitions only.

You can split a diskette into 2 or more parts (partitions) and switch between by a command. Every partition have to be formatted bevore use.

Have a look in die 1581 Manual, see here:
http://www.zimmers.net/anonftp…drives/1581-manual.txt.gz

Chapter: 6.8. Partitions and Sub-Directories

6.8. PARTITIONS AND SUB-DIRECTORIES

The 1581 allows the user to create partition areas on the disk.
Partitions were originally implemented to provide a mechanism for
easily protecting a particular section of the disk. That is
useful for permanently allocating part of the disk for things
such as BOOT sectors, CP/M work area, or reserving space for user
defined random files.
Normally, sectors on the disk can be marked as used by setting
the appropriate bit in the RAM (most easily done with the BLOCK-
ALLOCATE command). That prevents them from being overwritten. A
VALIDATE command, however, will de-allocate this area. To protect
these special blocks from being de-allocated during a VALIDATE,
place them in a user defined partition area. The VALIDATE command
in the 1581 automatically skips over file entries that are
partition files (file type = CBM), which guarantees the intended
area is, and remains, allocated.
Partition areas are given names by the user when first created.
They appear in the main directory as file type CBM.
A partition area is created by the following command:

PRINT#15,"/0:partition name,"+CHR$(starting track)+CHR$
(starting sector)+CHR$(<# of sectors)+CHR$(># of sectors)+",C"

Large enough partitions can also be used as sub-directories.
There are, however, certain limitations if a partition area is to
be used as a sub-directory area.

1) The partition are must be at least 120 sectors in size.
2) The starting sector must be 0.
3) The ending sector must be a multiple of 40.
4) The area to be allocated cannot contain track 40 (the
original system track).

Partitions can also be created with a partition. This means
that sub-sub-directories can be created if their partitions meet
the above rules. Graphically, it looks like this:

ROOT (/)
|
---------------------------------- ... ----------
| | | |
/0:PART1 /0:PART2 /0:PART3 ..... /0:PARTn
|
---------------------
| |
/0:PART2 /0:PART2
/0:PART21 /0:PART22

Partition areas which meet the qualifications of being a sub-
directory can then be selected by the following command:

PRINT#15,"/0:partition name"

Once selected, the partition are cannot be used as a sub-
directory until it is formatted. The HEADER or NEW commands are
used to format this sub-disk area. Make sure that you have
successfully selected this partition area before formatting. If
not, the wrong directory area will be reformatted. You can check
if the area was successfully selected by checking the error
channel. If everything went OK, the error channel would read:

02, SELECTED PARTITION,first track#,last track#

If the area you attempt to select does not meet the
qualifications of a sub-directory, then the error channel would
return:

77, SELECTED PARTITION ILLEGAL,00,00

Only one level of sub-directory can be selected at a time. To
get from the ROOT to PART21 you would have to execute the command
twice.

PRINT#15,"/0:PART2"
PRINT#15,"/0:PART21"

Directories can only be traversed in the forward direction. To
get to sub-directory which is on a node above the presently
selected node of the tree, you must select the ROOT directory and
work your way down the tree, selecting a branch at a time. To get
to the ROOT directory directly from any node type:

PRINT#15,"/"

When the user selects a particular sub-directory area, it then
becomes the default working area. Accesses to the disk for
directories, loading files, saving files, etc., will all be done
within this area. Files outside of the selected area are
effectively invisible.
File and local BAM information for sub-directories are stored
within the sub-directory areas themselves. The information is
stored on the first allocated track of the partition area, and
has the same format as track 40. When creating partitions and
sub-directories within sub-directories it is the responsibility
of the user to make sure that he doesn't overwrite this
information! The DOS only checks to make sure that you don't
attempt to overwrite this information for the ROOT directory
(track 40). It is up to the user to make sure that this
information isn't corrupted in the sub-directories.
Partitioned areas can be freed up simply by SCRATCHING the
partition file entry in the appropriate directory. If the
partition was being used as a sub-directory, all of the files in
that sub-directory will be lost.