INT 2D - DTown Utilities v1.40+ - POP UP

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