The 74HC and 74HCT280 are 9-bit odd/even parity generators or checkers. These devices are silicon-gate CMOS devices which are pin compatible with low power Schottky TTL (LSTTL) and comply with JEDEC ...
When it comes to AVR UART configuration, it is required to define the packet format a transmitter is going to transmit, and packet format is defined by character size, parity bits and stop bits.