DuoDisk interface

[travis@cluracan.org (Ward C. Travis)]

All right, I found a DuoDisk and it's in excellent shape. Problem is, I
sold my original Apple ][ over a decade ago back when the hip-happening
disk was still the Disk ][. So I've never seen a DuoDisk interface in my
life. Anyone who can point me at a good FAQ about this, or describe what I
need to get the DuoDisk up and running on an Apple ][+, will be thanked
massively. If it turns out that the DuoDisk is meant for the Lisa or only
for the /// systems, then, well tell me and I'll thank you for that :-) If
it's a parallel interface or serial interface, I'm in search of a
'driver'... I haven't opened it up yet beyond dusting it and seeing the
2003s in there, so I haven't really looked at its innards.

PS: Collectors: If you have an Apple ][ with serial number 11144, tell me
how it is doing!