The SN75ALS181NSR is a Differential Driver and Receiver designed for bidirectional data communication on multipoint bus transmission lines. The design provides for balanced transmission lines and meets TIA/EIA-422-B and TIA/EIA-485-A, CCITT recommendations V.10, V.11, X.26 and X.27. It combines a 3-state differential line driver and a differential-input line receiver that operate from a single 5V power supply. The driver and receiver have active-high and active-low enables, respectively, that can be connected together externally to function as a direction control. The driver differential outputs and the receiver differential inputs are connected to separate pins for greater flexibility and are designed to offer minimum loading to the bus when the driver is disabled or VCC=0. These ports feature wide positive and negative common-mode voltage changes, making the device suitable for party-line applications.