In the movie it looked like there was a clear wrap over the credit card, with an IDE cable connected to the Portfolio. The Portfolio did actually come with a parallel port.
In T2 it was probably just for show, but it may have been...
Yes it is the palmtop John Connor used to break credit card pin numbers. There was also that scene in the arcade at the start of the film where Connor is playing Missile Command (Atari). I don't know if Atari had any advertising hand in...
I was browsing the Atari museum and found this palmtop computer the Portfolio (1989). Quite a neat little device for its day, running an 8088 chip at 4mhz. The Psion was the first palmtop but I think the Portfolio was the first to have...