Like the theme music, the "Jeopardy!" set changed over the years. The original game board was exposed behind a curtain. The clues were printed on clue cards, which were shown as a player asked for a certain clue and its value. In 1978, the cards were dropped in favor of flipping panels which had the dollar value on one side and the clue on the other. Also, the curtain was changed to double-slide panels. When the show came back in 1984, the game board was changed again. This time it was made up of 30 television screens for each clue in the categories. In 1991, the original screens were changed to larger screens. In 2006, the screens were changed to a projection video wall. Then in 2009, the video wall was changed to 36 HD flat-panel screens.