The 6-DE-65/104RS board supports a single PCI board from a PC/104Plus stack. The RS model positions the PCI slot perpendicular to the PC/104 stack.

The 6-DE-65/104RS board has the advantage of mounting the PCI board "outside" of the stack area -- allowing other PC/104 boards to be stacked on top.  The RS version may be placed anywhere in the stack (placing it low in the stack results in a lower total height).

The PCI slots are normally configured as slot 0; however, other options are available.