Hi,
if I remember correctly there were two connectors on the back? I think there was a usb connector? but the usb software was never finalised due to a licensing problem so never used (it was overtaken by the 7k next).

However there was a 26 pin connector and the unit was supplied with a breakout cable for this socket. One end was the parallel printer type cable which went to port on pc or laptop and used the Techmanager6000 program to do the housekeeping on the hard drive.

The other end was 4 audio outs or 2 stereo outs which could output stereo drums, stereo accomp, stereo bass, or 4 individual parts from the sequencer. The selected parts could be muted from the internal speakers and main outs for an external mixer, and you could set the expression pedal to affect none, one or both outputs. Also the settings could be set to be global or you could have individual settings for each save, so loading different songs would enable different output settings according to taste.

It was ridiculously expensive but I really enjoyed using it in my 6k and then 6k5 with laptops at the time, but it took only a little time to appreciate the SD system on the 7k which effectively gave 99% of the practical uses at virtually no extra relative cost. The SD storage, usb and digital audio capability made the 7k a large step in value for money compared to earlier generations when you look back now.