Context: In 1974, L. Ottens, director of the audio division of Philips, started a small group with the aim to develop an analog optical audio disc with a diameter of 20 cm and a sound quality superior to that of the vinyl record. However, due to the unsatisfactory performance of the analog format, two Philips research engineers recommended a digital format in March 1974. In 1977, Philips then established a laboratory with the mission of creating a digital audio disc. The diameter of Philips's prototype compact disc was set at 11.5 cm, the diagonal of an audio cassette.

Question: In what year did Philips institute a laboratory to create a digital audio disc?
Answer: 1977

Question: What was the proposed diameter for the original compact disc?
Answer: 11.5 cm

Question: What year did Philips propse the idea of a digital audio format?
Answer: 1974

Question: Who was the director of the Philips audio division in 1974?
Answer: L. Ottens

Question: What Philips engineer recommended a digital format?
Answer: Unanswerable

Question: What was the 20cm diameter based on?
Answer: Unanswerable

Question: What year was the digital audio disc released?
Answer: Unanswerable

Question: How many engineer recommended the 11.5 cm diameter?
Answer: Unanswerable

Question: Who was the director of Philips by 1977?
Answer: Unanswerable