30H   DOS version number              3305H   ID of boot drive
3306H actual DOS version              CONFIG  start up menu choice
59H   recent error information        COMSPEC COMMAND.COM load path

2aH   current date                    INT 1cH detect timer tick
2cH   current time                    INT 28H detect DOS Idle state

19H   current default disk            INT 11H       BIOS equipment list
47H   current default directory       INT 15H c0H   BIOS configuration info

2fH   current DTA address             INT 15H 5300H APM installed state
34H   InDOS addr (reentrancy state)
35H   current value of an INT vector  INT 2fH 1700H Windows Enh386 active
51H   current PSP (active program)    INT 2fH 1700H Windows/Clipboard state
52H   List Of Lists (misc DOS vars)   INT 2fH 1687H DPMI installed state
INT 2fH 4b02H Dosshell installed state
54H   disk verify mode
3300H Ctrl-Break checking state       INT 33H 0000H mouse installed state
                                                                              

System Information Functions