High-definition television:

Additionally, cable-ready TV sets can display HD content without using an external box. They have a QAM tuner built-in and/or a card slot for inserting a CableCARD.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". What kind of built-in tuner will allow a cable-ready TV to display HD content without an external box?
QAM