System Information Functions

 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
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