You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
High-definition_television

Context:
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.

Question:
HD content can be displayed by cable-ready TVs without using what?

an external box