Series 2 requires the digital converter box to record from antenna and only on 1 channel.
Series 3 (models TCD648, TCD652, and TCD658) and Premiere (models TCD746320, TCD746500, TCD748000) does record from 2 channels at once from antenna or cable or from 1 of each.
But, Premiere 4 (TCD750, TCD758) can only work on digital cable, no antenna.
Original S1 (Recycle Heaven)
Series 2 (PLS, sold)
TiVo HD (XL, PLS, "652")
Juliet Basic (4XL, PLS)
The TiVo Apocalypse begins on Sat 2013 Feb 16 00:00 GMT!