Abstract: A display monitor for monitoring data flowing on the avionics data buses of an aircraft includes an interface card (53) for interfacing a PC (51) to avionics buses (31, 33, 35, 37, 39) and a set of discrete input/output lines (63). The interface card (53) includes a series of ARINC receiver/transmitters (65, 67, 69, 71), a programmed CPU (55), a primary memory (59) and a dual port I/O memory (61). The ARINC receiver/transmitters provide communication paths to the avionics data buses and the dual port I/O memory (61) provides a communication path to the PC data bus (75). The interface card CPU (55) continuously scans the ARINC receiver/transmitters looking for avionics data and, at greater intervals, the discrete input lines (63) and the dual port I/O memory (61) looking for commands. ARINC data is initially "dumped" into the card primary memory (59) and later transferred to the dual port shared memory (61) from whence it is transferred to a work buffer in the PC.