Features
1) Built-in bias resistors enable the
   configuration of an inverter circuit
   without connecting external input
   resistors (see equivalent circuit).
2) The bias resistors consist of thin-film
   resistors with complete isolation to allow positive biasing of the
   input. They also have the advantage of 
   almost completely eliminating parasitic effects.
3) Only the on/off conditions need to
   be set for operation, making device
   design easy.