INT 16,2 - Read Keyboard Flags
AH = 02 on return: AL = BIOS keyboard flags (located in BIOS Data Area 40:17) │7│6│5│4│3│2│1│0│ AL or BIOS Data Area 40:17 │ │ │ │ │ │ │ └──── right shift key depressed │ │ │ │ │ │ └───── left shift key depressed │ │ │ │ │ └────── CTRL key depressed │ │ │ │ └─────── ALT key depressed │ │ │ └──────── scroll-lock is active │ │ └───────── num-lock is active │ └────────── caps-lock is active └─────────── insert is active