Format of current directory structure (CDS) (array, LASTDRIVE entries):
Offset  Size    Description
 00h 67 BYTEs   ASCIZ path in form X:\PATH (local) or \\MACH\PATH (network)
 43h    WORD    drive attributes (see also note below and AX=5F07h)
                bit 15: uses network redirector  \ invalid if 00, installable
                    14: physical drive           / file system if 11
                    13: JOIN'ed   \ path above is true path that would be
                    12: SUBST'ed  / needed if not under SUBST or JOIN
 45h    DWORD   pointer to Drive Parameter Block for drive (see AH=32h)
---local drives---
 49h    WORD    starting cluster of current directory
                0000h = root, FFFFh = never accessed
 4Bh    WORD    ??? seems to be FFFFh always
 4Dh    WORD    ??? seems to be FFFFh always
---network drives---
 49h    DWORD   pointer to redirector or REDIRIFS record, or FFFFh:FFFFh
 4Dh    WORD    stored user data from INT 21/AX=5F03h???
------
 4Fh    WORD    offset in current directory path of backslash corresponding to
                  root directory for drive
                this value specifies how many characters to hide from the
                  "CHDIR" and "GETDIR" calls; normally set to 2 to hide the
                  drive letter and colon, SUBST, JOIN, and networks change it
                  so that only the appropriate portion of the true path is
                  visible to the user
---DOS 4.x---
 51h    BYTE    ??? used by network
 52h    DWORD   pointer to IFS driver for this drive, 00000000h if native DOS
 56h    WORD    ???
Notes:  the path for invalid drives is normally set to X:\, but may be empty
          after JOIN x: /D in DR-DOS 5.0 or NET USE x: /D in older LAN versions
        normally, only one of bits 13&12 may be set together with bit 14, but
          DR-DOS 5.0 uses other combinations for bits 15-12: 0111 JOIN,
          0001 SUBST, 0101 ASSIGN

Format of DR-DOS 5.0-6.0 current directory structure entry (array):
Offset  Size    Description
 00h 67 BYTEs   ASCIZ pathname of actual root directory for this logical drive
 43h    WORD    drive attributes
                1000h SUBSTed drive
                3000h??? JOINed drive
                4000h physical drive
                5000h ASSIGNed drive
                7000h JOINed drive
                8000h network drive
 45h    BYTE    physical drive number (0=A:) if this logical drive is valid
 46h    BYTE    ??? apparently flags for JOIN and ASSIGN
 47h    WORD    cluster number of start of parent directory (0000h = root)
 49h    WORD    entry number of current directory in parent directory
 4Bh    WORD    cluster number of start of current directory
 4Dh  2 BYTEs   used for media change detection (details not available)
 4Fh    WORD    cluster number of SUBST/JOIN "root" directory
                0000h if physical root directory