User`s guide

Only one Directory Label can exist in a drive's directory. The Directory Label name
and type fields are not used to search for a Directory Label; they can be used to
identify a disk. A Directory Label can be created, or its fields can be updated by
BDOS function 100, Set Directory Label. This function can also assign a Directory
Label a password. The Directory Label password, if assigned, cannot be circum-
vented, whereas file password protection is an option controlled by the Directory
Label. Thus, access to the Directory Label password provides a kind of super-user
status on that drive.
The nonbanked version of CP/M 3 does not support file passwords. However, it
does provide password protection of directory labels. The CP/M 3 RSX, DIRLBL.RSX,
which implements BDOS Function 100 in the nonbanked version of CP/M 3, pro-
vides this support.
The BDOS file system has no function to read the Directory Label FCB directly.
However, the Directory Label data byte can be read directly with the BDOS Function
101, Return Directory Label. In addition, the BDOS Search functions, with a ? in the
FCB drive byte, can be used to find the Directory Label on the default drive. In the
directory, the Directory Label is identified by a drive byte value, byte 0 in the FCB,
equal to 32, 20H.
2.3.7 File Passwords
Only the banked version of CP/M 3 supports file passwords. In the nonbanked
version, all BDOS functions with password related options operate the same way the
banked version does when passwords are not enabled.
Files can be assigned passwords in two ways: by the Make File function or by the
Write File XFCB function. A file's password can also be changed by the Write File
XFCB function if the original password is supplied.
Password protection is provided in one of three modes. Table 2-4 shows the differ-
ence in access level allowed to BDOS functions when the password is not supplied.
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2.3 BDOS File System CP/M 3 Programmer's Guide