Index for interrupt INT 2B

Table of Contents by Order
2B - INT 2B - DOS 2+ - RESERVED
2B - INT 2B - IBM ROM-DOS v4.0 - ???

INT 2B - DOS 2+ - RESERVED
Note:	this vector is not used in MS-DOS versions <= 6.22, and points at an
	  IRET instruction

INT 2B - IBM ROM-DOS v4.0 - ???
	AH = function
	    00h ??? (modifies data in IBMBIO.COM)
	    01h internal operations
	    02h ???
		AL = index (00h-0Ch)
		Return: AX = ??? or (CMOS 2Dh and CMOS 2Eh)
	    03h get ??? data
		Return: AX = (CMOS 2Dh and CMOS 2Eh)
			BX = FFFFh
	    other does nothing
Note:	function 03h is called by ROMSHELL.COM; if BX != 0, then the ES:DI from
	  INT 2F/AX=1982h points at valid data
SeeAlso: INT 2F/AX=1982h