Bitfields for DoubleDOS keyboard control flags:
Bit(s)	Description	)
 0	menu
 1	exchange
 2	entire keyboard enable/disable
 3	Ctrl-C
 4	Ctrl-PrtSc
 5	Alt/Erase
 6	Ctrl-Break
 7	Ctrl-NumLock
 8	shift-PrtSc
 9-13	undefined
 14	cancel key (clear keyboard buffer)
 15	suspend key
Note:	setting a enables the corresponding key or operatin, clearing a
	  disables it