INT 16 - KEYBOARD - GET EXTENDED SHIFT STATES (enh kbd support only)
	AH = 12h
Return: AL = shift flags 1 (same as returned by AH=02h) (see #00587)
	AH = shift flags 2 (see #00588)
Notes:	AL bit 3 set only for left Alt key on many machines
	AH bits 7 through 4 always clear on a Compaq SLT/286
	INT 16/AH=09h can be used to determine whether this function is
	  supported, but only on later model PSIBM PS/2, any model/2s
	many BIOSes (including at least some versions of Phoenix and AMIAmerican Megatrends, Inc.(American Megatrends, Inc.) A hardware, software and firmware company founded in 1985.) will
	  destroy AH on return from functions higher than AH=12h, returning
	  12h less than was in AH on entry (due to a chain of DEC/JZ
	  instructions)
SeeAlso: AH=02h,AH=09h,AH=22h,AH=51h,INT 17/AH=0Dh,MEM 0040h:0017h


Bitfields for keyboard shift flags 1:
Bit(s)	Description	(Table 00587)
 7	Insert active
 6	CapsLock active
 5	NumLock active
 4	ScrollLock active
 3	Alt key pressed (either Alt on 101/102-key keyboards)
 2	Ctrl key pressed (either Ctrl on 101/102-key keyboards)
 1	left shift key pressed
 0	right shift key pressed
SeeAlso: #00582,#00588,MEM 0040h:0017h,#M0010


Bitfields for keyboard shift flags 2:
Bit(s)	Description	(Table 00588)
 7	SysReq key pressed (SysReq is often labeled SysRq)
 6	CapsLock pressed
 5	NumLock pressed
 4	ScrollLock pressed
 3	right Alt key pressed
 2	right Ctrl key pressed
 1	left Alt key pressed
 0	left Ctrl key pressed
SeeAlso: #00587,MEM 0040h:0018h,#M0011