This concept takes an interesting approach to a fold-down desktop system.  Although its appearance is that of a laptop, this system was meant to be more of a desktop system.  A very interesting note is the "Palm Rest" which was a concept first put into production be Apple Computer in the early 1990's, however it appears Atari's own Industrial Design group was well ahead of not only Apple but the entire computer industry with this simple yet well touted ergonomic feature.   This concept off add-ons has a look that is reminiscent of the Intellivision add-on design.