M-Nav

Hello everyone.
New to the group. I have a Pegasus that hasn't flown in many years and
I'm getting her ship-shape after a new annual and a clean bill-of-
health. The glider has an older M-Nav50 computer and I was wondering
if anyone can tell me something about these computers, i.e., what
functions does it perform (speed to fly, best glide, etc.), I'm also
wondering if I can interface this old a model to any current PDA,
etc., or will there be compatibility issues? I guess I'm trying to
assertain whether it's worth saving, or should I bite the bullet and
buy a new one. I'd like to try to make it work, at least for the time
being. I don't fly competitions....it would mainly be for XC. Thanks.
Dave