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 #0511)
   AH = shift flags 2 (see #0512)

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
   many BIOSes (including at least some versions of Phoenix and AMI) 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)

See Also: 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 0511)
 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

See Also: #0506,#0512,MEM 0040h:0017h,#M010

Bitfields for keyboard shift flags 2:
Bit(s) Description (Table 0512)
 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

See Also: #0511,MEM 0040h:0018h,#M011