Keyboard driver
		---------------

KBD_@		( -- code ) get scancodes for pressed keys from keyboard.
KBD_down?	( key -- result ) check is key with specified scancode
		currently pressed down. 
KBD_SC2FSCII	( code -- FSCII ) convert key scancode into FSCII code,
		or in FSK (Fifth standard keycode). 
KBD_F@		( -- FSCII ) read pressed key FSCII or FSK, returns -1 if no
		keys are pressed.
KBD_FW@         ( -- FSCII ) read pressed key FSCII or FSK, if no keys is
                are pressed then waits until there is.

                FSK
                ---
In HEX.

FC      backspace
FD      TAB
FE      enter
FF      space

400     ESC
401 ... F1 ...
410     up
411     right
412     down
413     left
414     INS
415     DEL
416     home
417     end
418     PG/UP
419     PG/DN