The HI-8581 and HI-8589 from Holt Integrated Circuits are silicon gate CMOS devices for interfacing a 16-bit parallel data bus directly to the ARINC 429 serial bus. Both devices provide two receivers, an independent transmitter and line driver capability in a single package. The receiver input circuitry and logic are designed to meet the ARINC 429 specifications for loading, level detection, timing, and protocol. The transmitter section provides the ARINC 429 communication protocol and the line driver circuits provide the ARINC 429 output levels. The 16-bit parallel data bus exchanges the 32-bit ARINC data word in two steps when either loading the transmitter or interrogating the receivers. The data bus interfaces with CMOS and TTL.