The Atari 1200XL-S system was simply a version of the 1200XL that was shown at Consumer Electronic Shows to guage users interest in the system and its configuration, most notable is the fact that the cartridge interface is located on the top of the unit as opposed to the side on a normal 1200XL.   An interesting note about this system is the fact that the rear of the case (Image will be made available later) has cut-outs for a PBI interface and has 2 telephone jacks (hmmm, could this have been the first case design for the 1400XL ?)