Used by the routine at 5F3C. Can be either;

• 01
• 02
• 03

This represents which background is shown.

Buffer that holds the currently processed background data depending on the background reference value.

Background_Reference	Background Data
01	Background_1_Addresses
02	Background_2_Addresses
03	Background_3_Addresses

Populated from one of 5F53, 5F62 or 5F71.

Points to the address containing the player 1 control address mappings.

When player 1 is using the keyboard, these byte pairs will be populated with the corresponding keys.

Points to the address containing the player 2 control address mappings.

When player 2 is using the keyboard, these byte pairs will be populated with the corresponding keys.

See Key_Data for key mappings.

See Key_Data for key mappings.

See Key_Data for key mappings.

See Key_Data for key mappings.