Int 2D  - Dtown Utilities V1.40+ - Pop Up                                  [U]

   AL = 21h
   BL = which utility to bring up
       00h active utility
       01h help screen
       0Ah ASCII table
       0Bh memory view
       0Ch CPU status
       0Dh calculator
       0Eh miscellaneous
       0Fh file viewer
       10h disassembler

Return: AL = status
       00h already active
       FFh popped up successfully
   BX = 0000h

Note:  this function is only available if the extended API has been installed
     in the resident portion

See Also: INT 2D/AL=10h"DTown",INT 2D/AL=20h,INT 2D/AL=50h