unsigned _bios_printer(unsigned cmd,unsigned port,unsigned data)

	- prototype in bios.h

	- cmd 	= _PRINTER_WRITE   print character  (INT 17,0)
		= _PRINTER_INIT	   initialize printer port  (INT 17,1)
		= _PRINTER_STATUS  read port status  (INT 17,2)
	- port	= printer port;	0=LPT1, 1=LPT2
	- data	= value to write

	- returns status of printer (INT 17, AX reg, AH contains status)
	- Turbo C uses biosprint()
	- see  INT 17