INT 2F U - DOS 3.0+ internal - CHECK IF CHARACTER DEVICE                        
	AX = 1223h
	DS = DOS DS
	SS = DOS DS (must be using a DOS internal stack)
	SDA+218h (DOS 3.10-3.30) = eight-character blank-padded name
	SDA+22Bh (DOS 4.0-6.0) = eight-character blank-padded name
	SDAsee Swappable Data Area file attribute field set
	direction flag clear (i.e. CLD)
Return: CF set if no character device by that name found
	CF clear if found
	    BH bits 4-0 copied from low byte of device attribute word
	    BH bit 5 set, bits 7-6 clear
Notes:	can only be called from within DOS
	the check is skipped (always says "not device") if the volume ID bit
	  of the file attribute field is set on entry
SeeAlso: INT 21/AX=5D06h,INT 21/AX=5D0Bh