About Triggers
In fMRI the scanner paces the experiment, and your experimental software will have to catch scanner pulses and sync the trials to them. In MEG the recording is basically continuous, so to know when a trial happened, and what was actually presented, you will have to send triggers to be recorded with the brain signals.
Triggers can be send through the PIO card or the parallel port. E-Prime can only use the parallel port, DMDX only the PIO card. On the parallel port 8 channels are available for triggers, allowing a total of 255 different trigger values to be send. If you need more, you will need to send several triggers in each trial.
There's a box on the table, next to the stimulus computer, to which the trigger pulses have to be send. Two other boxes are connected to the parallel port and the PIO card. The appropriate connections can be made with patch cables.