TiVo Premiere Manual page 8

Dual tuner. A tuner is a device found inside DVRs, TVs, cable
boxes — anything designed to receive TV signals, including the
TiVo Premiere. A tuner picks one channel to display; it "tunes"
to that channel. Your TiVo Premiere is a "dual tuner" device,
meaning that it has two tuners inside and can record two shows
at once. Pressing the Live TV button while in live TV will swap
between your two tuners.
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CableCARD Decoder. A CableCARD decoder allows your
TiVo Premiere to receive digital cable channels without a cable
box. If you subscribe to digital cable, you must request one
Multi-Stream CableCARD (M-CARD) from your cable
company. One M-CARD will let you watch and record two
shows at once.
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