75173, LTC488 Quad RS485 line receiver. Note the unusual ORed output enables. +----------+ +-------------------+ B1 |1 +--+ 16| VCC | A-B | OE|/OE| Y | A1 |2 15| B4 |-------+---+---+---| Y1 |3 14| A4 |>+200mV| 1 | X | 1 | OE |4 13| Y4 |>+200mV| X | 0 | 1 | Y2 |5 75173 12| /OE |<-200mV| 1 | X | 0 | A2 |6 11| Y3 |<-200mV| X | 0 | 0 | B2 |7 10| A3 | X | 0 | 1 | Z | GND |8 9| B3 +-------------------+ +----------+ [This information is part of the GIICM]