What's a Titan Neptune card do?

[Andrew Brenner <brenner@earthling.net>]

Hello all.  I just picked up a IIe in very good shape from a local
thrift store. I ended up getting the IIe itself, a duodisk drive(s), a
monitor II, an imagewriter, and two disk boxes full of floppies in
addition to a small stack of software in their appopriate folders /
binders that they originally came in.

I popped open the lid to see what's inside and the card in the "aux
connector" slot was apparently made by Titan Technologies.  The only
other thing that is printed on the card is the word 'Neptune'.  I'm
guessing this is the name of the card.  Unfortunately, I don't know what
this card does. This is the first IIe I've ever had and luckily I did
get the manual with it, but I don't know enough to really notice any
change in operation due to this card.  Any help would be greatly
appreciated of course. Thanks!

--andrew--