Wolfgang's IIc is used to drive the mysterious circuit board and ultimately forms an integral part of their spacecraft.
The Apple's graphical abilities have been considerably enhanced.
Year of feature (shown above)
Also, in the movie the IIc has a compartment for holding a 9 volt battery.
And the IIc keeps going for a long, long time on that 9-volt battery.
And that's a very young River Phoenix behind those glasses.