Bubble Bobble (NES)/RAM map

The following article is a RAM map for Bubble Bobble (NES).

Global Variables

• 0401 - Current Level (Level 1 = $01)
• 045D - Super Bubble Bobble switch
• 04C4 - Altering this changes the enemy sprites. Probably an offset position for reading data from the pattern image.

Menu Variables

• 0402 - Option selected on main menu
• 0502-0506 - Password letters (A-J = $00-$09)

Player Variables

• 002E - P1 remaining lives
• 003F - P1 invincibility timer (odd = invisible, even = visible)
• 0042 - P2 remaining lives
• 0053 - P2 invincibility timer (odd = invisible, even = visible)

Counter Variables

Counter variables determine what kind of special item will appear at the start of the next level, according to specific player actions. When a counter reaches a certain threshold (from a table in ROM), the corresponding item code is loaded in $40B and the counter is reset to 0. If more than one counter reach their threshold, the lowest in the list has priority.

• 435 - Bubbles Blown
• 436 - Empty Bubbles Popped
• 437 - Jumps on Bubble
• 438 - Fire Bubbles Popped
• 439 - Water Bubbles Popped
• 43A - Times Fallen Through Floor
• 43B - Enemy Items Taken
• 43C - Enemies Killed by Water
• 43D - Enemies Killed by Lightning
• 43E - Enemies Killed by Fire
• 43F - Special Items Taken
• 440 - Lightning Bubbles Popped
• 441 - Enemy Combo Kills (2 or more)
• 442 - Point Items Taken
• 443 - Letter Bubbles Popped

Bonus Round Variables

• 042F - Amount of remaining treasures during Bonus Game
• 0430 - Bonus Round timer
• 0431 - P1 treasures collected in Bonus Round
• 0433 - P2 treasures collected in Bonus Round
• 045F - Bonus Round switch (set to $01+ to activate the bonus game, as if picking up the bottle)

Level Variables

• 0405 - Queue for EXTEND letters (Only 3 will come per level, any queue excess will be cleared at the beginning of the next level with openings)
• 040D - Timer countdown until "Hurry!" appears. This set to 040E at the beginning of each level.
• 040E - What the "Hurry!" timer countdown (040D) is set to at the beginning of a level. Varies from level to level.
• 044D - Remaining levels to be skipped by an umbrella. If > 0 when all the enemies on the level are defeated, you will being skipping levels. You can only skip 31 levels max. If the variable is set above $1F(31), skipping will occur again after the defeat of the enemies. This will continue until the variable = 0.
• 045E - Timer going up (Item appearances/disappearances may be relative to it)
• 04CD - Point Item position [on Level 1, it positions the item diagonally from the upper-left corner ($00) to the lower-right corner ($FF)]
• 04CE - Appearance of Elemental Bubbles ($00-$1F = Nothing/????, $20-$3F = Water Bubbles, $40-$5F = Fire Bubbles, $60+ Fire Bubbles over Water Bubbles and other odd combinations)

End Boss Variables

• 006F - Super Drunk's HP

Miscellaneous Variables

• 0445-044B - Variables representing each digit of the last scorer's score.
  

- 0445 is millions
- 0446 is hundred thousands
- 0447 is ten thousands
- 0448 is thousands
- 0449 is hundreds
- 044A is tens
- 044B is ones