Entering the cellar where the king keeps his barrels of wine brings the last part of the adventure to life. Three things happen:

• Timer 9 (C9B2) is started with a count of 3. This is the timer that controls the side door of the Lonely Mountain (object 11), far away in room 42: it makes 'a loud crack and a hole appears about three feet from the ground' for one turn in every five (A985), after which 'the hole vanishes' (A968), unless it has been opened. The count of 3 means the first appearance happens two turns after Bilbo enters the cellar.
• The dragon (object 60) is switched on by writing its number, $3C, into its empty slot in the character table at C9F2 - unless it is already dead. Until now the dragon has been lying inert in the lower halls; from now on its behaviour program (A5D5, A591, A5BB) runs every turn.
• Bard (object 70) is switched on in the same way, by writing $46 into the slot at $C9EB, unless he is dead. He starts waiting for orders (A79F).

So the dragon cannot threaten Bilbo, and Bard cannot help him, until Bilbo has reached the Elvenking's cellar. Like the butler's handler (C693), this runs every time Bilbo enters the cellar, restarting the side door timer at 3 each time.