Err, not necessarily. I'm rather thinking that the corresponding LCD projector ("beamer") might have included or at least supported a "presenter", i.e. a wireless, handheld mini-trackball or hat-switch type pointing device, whose signals are relayed to the host system via the respective pointing device interface. As only one of these interfaces is needed at a given time (ADB when connected to a Mac, either RS232 or PS/2 for a legacy PC, or USB for a modern one), it kind of makes sense to bring these out in a single connector (in this case, the DE15) and include the different adapter cables for connecting it to the host system. I got a similar set of cables some years ago, these had a not-quite-MiniDIN connector at the projector end and either DE9, MiniDIN-6 or USB on the other. They were factory labelled as belonging to an ASK C105. If so, very usefor for somebody having the corresponding projector, not so much for anyone else. Hope this helps - so long, Arno Kletzander