This is The Hobbit's famous 'independent characters' system. Every character in the table at C9BA gets a turn after the player.

Each entry of that table is 7 bytes: the character's object number (0 if the character is dead or gone), a count used by 99B4, the address of the character's current place in its behaviour program, the address of its reaction table, and a 'stubbornness' value used by 8F9E.

For each living character, the character becomes the current actor (B5DB, $B5FC) and the room it starts the turn in is noted ($B5E7). Output is switched on only if Bilbo can see the character (9D77), so the player sees only what happens in front of him. If Bilbo is in the dark, the first character to do anything in his room produces 'you hear a noise.' instead (AF19).

A character that is inside something (held by an object rather than standing in a room) tries to get out first (9A71).

Then the character's behaviour program is run. Each instruction starts with a byte whose low nibble is its type and whose high bits are flags: bit 4 'jump afterwards to the address that follows', bit 5 'do this only once' (the instruction is cleared to 0 after use), bit 6 'do not take orders at this point'. The types are:

• 0-3: do an action. The next three bytes are the action, the target and the instrument (9883). If bit 0 of the flags is set, the next two bytes are instead the address of a routine that does something special - most of the routines in the range A406-A91B are such character routines.
• 4: do an action without objects, such as moving in a direction (98CF). An action of $FF just jumps.
• $0C: change the character's reaction (99FB).
• $0E: jump to the address that follows.
• $0F: choose at random one of the behaviours in the reaction table (99B4).
• anything else: go back to the first behaviour in the reaction table.

Before the program, if the player has given the character an order (88FD) and the current instruction allows it (bit 6 clear), the order is obeyed instead (8907, 9929).

A character stops after 6 instructions in one turn (9769). At the end the player becomes the actor again, with output switched on.