TC: int bioskey( int cmd )

	- prototype in bios.h

	- keyboard operations
	- cmd	= 0  return next keystroke w/o echo  (INT 16,0)
		= 1  test if key waiting;  0=none  (INT 16,1)
		= 2  return shift key status  (see INT 16,2)


	- AND returned value with 0x00FF to get ASCII value
	- Ctrl-Break causes "while (!bioskey(1))" to loop infinitely in
	  Turbo C 2.0 and earlier since it places a zero in the keyboard queue
	- MS C uses _bios_keybrd()
	- see	INT 16