INT 21 - DOS 3.2+ - IOCTL - GENERIC CHARACTER DEVICE REQUEST

	AX = 440Ch
	BX = device handle
	CH = category code (see #01545)
	CL = function number (see #01546)
	DS:DX -> parameter block (see #01547,#01548,#01549,#01550,#01551,#01552)
	SI = parameter to pass to driver (European MS-DOS 4.0, OS/2 comp box)
	DI = parameter to pass to driver (European MS-DOS 4.0, OS/2 comp box)
Return: CF set on error
	    AX = error code (see #01680 at AH=59h/BX=0000h)
	CF clear if successful
	    DS:DX -> iteration count if CL=65h
	    SI = returned value (European MS-DOS 4.0, OS/2 comp box)
	    DI = returned value (European MS-DOS 4.0, OS/2 comp box)
Note:	DR DOS 3.41 and 5.0 return error code 16h on CL=45h,65h if the device
	  does not support a retry counter
SeeAlso: AX=440Dh"DOS 3.2+",INT 2F/AX=0802h,INT 2F/AX=122Bh,INT 2F/AX=14FFh
SeeAlso: INT 2F/AX=1A01h