NewtonConnectionUtilities (NCU)is the program that shipped with the MessagePad2000 and MessagePad2100. It's only available for Windows and Mac OS <= 9, and as it was written by Apple, so it hasn't been updated in years. That having been said, NewtonConnectionUtilities will run very happily in Classic mode under Mac OS X 10.2. NewtonConnectionUtilities only connects to OS 2.x machines, and only via serial, LocalTalk, or EtherTalk. For OS 1.x machines, use NewtonConnectionKit.

Some newer programs are available as well, and so are programs for other platforms.