Format of List of Lists:
Offset  Size    Description
 -12    WORD    (DOS 3.1+) sharing retry count (see AX=440Bh)
 -10    WORD    (DOS 3.1+) sharing retry delay (see AX=440Bh)
 -8     DWORD   (DOS 3+) pointer to current disk buffer
 -4     WORD    (DOS 3+) pointer in DOS code segment of unread CON input
                when CON is read via a handle, DOS reads an entire line,
                  and returns the requested portion, buffering the rest
                  for the next read.  0000h indicates no unread input
 -2     WORD    segment of first memory control block
 00h    DWORD   pointer to first Drive Parameter Block (see AH=32h)
 04h    DWORD   pointer to first System File Table (see below)
 08h    DWORD   pointer to active CLOCK$ device's header
 0Ch    DWORD   pointer to active CON device's header
---DOS 2.x---
 10h    BYTE    number of logical drives in system
 11h    WORD    maximum bytes/block of any block device
 13h    DWORD   pointer to first disk buffer (see below)
 17h 18 BYTEs   actual NUL device driver header (not a pointer!)
                NUL is always the first device on DOS's linked list of device
                drivers. (see below)
---DOS 3.0---
 10h    BYTE    number of block devices
 11h    WORD    maximum bytes/block of any block device
 13h    DWORD   pointer to first disk buffer (see below)
 17h    DWORD   pointer to array of current directory structures (see below)
 1Bh    BYTE    value of LASTDRIVE command in CONFIG.SYS (default 5)
 1Ch    DWORD   pointer to STRING= workspace area
 20h    WORD    size of STRING area (the x in STRING=x from CONFIG.SYS)
 22h    DWORD   pointer to FCB table
 26h    WORD    the y in FCBS=x,y from CONFIG.SYS
 28h 18 BYTEs   actual NUL device driver header (not a pointer!)
                NUL is always the first device on DOS's linked list of device
                drivers. (see below)
---DOS 3.1-3.3---
 10h    WORD    maximum bytes per sector of any block device
 12h    DWORD   pointer to first disk buffer in buffer chain (see below)
 16h    DWORD   pointer to array of current directory structures (see below)
 1Ah    DWORD   pointer to system FCB tables (see below)
 1Eh    WORD    number of protected FCBs (the y in the CONFIG.SYS FCBS=x,y)
 20h    BYTE    number of block devices installed
 21h    BYTE    number of available drive letters (largest of 5, installed
                block devices, and CONFIG.SYS LASTDRIVE=).  Also size of
                current directory structure array.
 22h 18 BYTEs   actual NUL device driver header (not a pointer!)
                NUL is always the first device on DOS's linked list of device
                drivers. (see below)
 34h    BYTE    number of JOIN'ed drives
---DOS 4.x---
 10h    WORD    maximum bytes per sector of any block device
 12h    DWORD   pointer to disk buffer info record (see below)
 16h    DWORD   pointer to array of current directory structures (see below)
 1Ah    DWORD   pointer to system FCB tables (see below)
 1Eh    WORD    number of protected FCBs (the y in the CONFIG.SYS FCBS=x,y)
                (always 00h for DOS 5.0)
 20h    BYTE    number of block devices installed
 21h    BYTE    number of available drive letters (largest of 5, installed
                block devices, and CONFIG.SYS LASTDRIVE=).  Also size of
                current directory structure array.
 22h 18 BYTEs   actual NUL device driver header (not a pointer!)
                NUL is always the first device on DOS's linked list of device
                drivers. (see below)
 34h    BYTE    number of JOIN'ed drives???
 35h    WORD    pointer within IBMDOS code segment to list of special program
                names (see below)
                (always 0000h for DOS 5.0)
 37h    DWORD   pointer to FAR routine for resident IFS utility functions
                (see below)
                may be called by any IFS driver which does not wish to
                service functions 20h or 24h-28h itself
 3Bh    DWORD   pointer to chain of IFS (installable file system) drivers
 3Fh    WORD    the x in BUFFERS x,y (rounded up to multiple of 30 if in EMS)
 41h    WORD    the y in BUFFERS x,y
 43h    BYTE    boot drive (1=A:)
 44h    BYTE    01h if 80386+, 00h otherwise???
 45h    WORD    extended memory size in K
---DOS 5.0---
 10h 39 BYTEs   as for DOS 4.x (see above)
 37h    DWORD   pointer to SETVER program list or 0000h:0000h
 3Bh    WORD    ??? pointer to function in DOS CS
 3Dh    WORD    ??? apparently 0000h if DOS loaded low, PSP of most-recently
                EXECed program if DOS in HMA
 3Fh  8 BYTEs   as for DOS 4.x (see above)