The cable card slot is on the bottom of the Roamio, just like the battery compartment of a remote where you open a cover to access it.
Series 2 (PLS, sold)
TiVo HD 1TB (157 HD Hrs, PLS, "652")
Roamio! Oh, wait, Its Juliet!
OTA! OTA! OTA!
The TiVo Apocalypse begins on Sat 2013 Feb 16 00:00 GMT!