Int 16 Fn 12  - Keyboard - Get Extended Shift States (enh Kbd Support Onl  [B]

   AH = 12h

Return: AL = shift flags 1 (same as returned by AH=02h) (see below)
   AH = shift flags 2 (see below)

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 PS/2s

See Also: AH=02h,AH=09h,AH=22h,AH=51h,INT 17/AH=0Dh

Bitfields for shift flags 1:
 bit 7 Insert active
 bit 6 CapsLock active
 bit 5 NumLock active
 bit 4 ScrollLock active
 bit 3 Alt key pressed (either Alt on 101/102-key keyboards)
 bit 2 Ctrl key pressed (either Ctrl on 101/102-key keyboards)
 bit 1 left shift key pressed
 bit 0 right shift key pressed

Bitfields for shift flags 2:
 bit 7 SysRq key pressed
 bit 6 CapsLock pressed
 bit 5 NumLock pressed
 bit 4 ScrollLock pressed
 bit 3 right Alt key pressed
 bit 2 right Ctrl key pressed
 bit 1 left Alt key pressed
 bit 0 left Ctrl key pressed