$CPU 8086          ' make compatible with XT systems
$LIB ALL OFF       ' turn off all PowerBASIC libraries
$ERROR ALL OFF     ' turn off all PowerBASIC error checking
$OPTIMIZE SIZE     ' optimize for smaller code
 $COMPILE UNIT      ' compile to a UNIT (.PBU)
'$COMPILE EXE       ' compile to a UNIT (.PBU)

DEFINT A-Z         ' Required for all numeric functions, forces PB to not
                   ' include floating point in UNIT (makes it smaller)
'/*------------------------------------------------------------------*/
$CODE SEG "MLIB5"
'/*------------------------------------------------------------------*/
' IS4DOS()
'     Returns: 0 = 4DOS is NOT loaded.
'              1 = 4DOS is loaded.
'     EXAMPLE:  T = IS4DOS
'/*------------------------------------------------------------------*/
FUNCTION IS4DOS() PUBLIC AS INTEGER
  !  mov AX, &hD44D
  !  xor BX,BX
  !  INT &h2F
  !  mov X,AX
  IF X=&H44DD THEN FUNCTION = 1 ELSE FUNCTION = 0
End Function
'/*------------------------------------------------------------------*/
'  $INCLUDE "C:\CODE\MLIB\MLIB.INC"
'  PRINT IS4DOS
'  Y$ = GETKEY