INT 16,12 - Extended Get Keyboard Status (AT+)

	AH = 12h

	on return:
	AH = BIOS keyboard flags (BIOS Data Area location 40:18)

		│7│6│5│4│3│2│1│0│  AH
		 │ │ │ │ │ │ │ └──── left CTRL key depressed
		 │ │ │ │ │ │ └───── left ALT key depressed
		 │ │ │ │ │ └────── right CTRL key pressed
		 │ │ │ │ └─────── right ALT key depressed
		 │ │ │ └──────── scroll-lock depressed
		 │ │ └───────── num-lock key depressed
		 │ └────────── caps-lock key depressed
		 └─────────── system request key depressed

	AL = BIOS keyboard flags (BIOS Data Area location 40:17)

		│7│6│5│4│3│2│1│0│  AL
		 │ │ │ │ │ │ │ └──── 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


	- available on AT and PS/2 machines with extended keyboard support
	- similar to INT 16,2

	- see	KB FLAGS