The DB101 display module can be added to the MC303 (See application notes AVR481, AVR482, and AVR483 on http://www.atmel.com/).
Connection
DB101 connects using 3 headers J5, J6 & J7 (respectively UART, SPI, and TWI).
Figure 1. DB101 Display Module
Communication
DB101 uses the Usart with ATxmega128A1 through J5 header.