Pythagoras
Enthusiast
I decided to dissassemble Taitos Bubble Memories this time, to find out the secret behind the "Extra Mode". What I found out is that it requires two conditions to unlock this mode.
When the game have been running for 10 hours, a counter starts to keep track of how many games that been played. The counter is saved to the NV-RAM after every game is finished, when 90 games or more been played the "Extra Mode" will be activated at the next startup of the game.
If you don't want spend the time and work
for this to be done, you can always cheat by taking a shortcut and burning a modified Eprom.
So let's make an eprom that can be used to write the required byte to the NV-RAM...
There is three Versions in Mame, the parent set is "bubblem". The required rom are for the different versions:
Japan Ver. 2.3 (Rom: e21-10.19)
Overseas Ver 2.4 (Rom: e21-20.19)
America 2.5 (Rom: e21-16.19)
The offset that need to be modified is the same for all three versions. Load the rom into a hexeditor and change the value at the offset: $40E5D from $00 to $5A.
This offsett is the NV-RAM defaults. So when you have programmed the modified rom, just enter service mode and select "Factory Setting". Exit the service mode to confirm that
the title screen now displays "Extra Mode". After this you are done and can put back the original eprom again.
Good Luck
When the game have been running for 10 hours, a counter starts to keep track of how many games that been played. The counter is saved to the NV-RAM after every game is finished, when 90 games or more been played the "Extra Mode" will be activated at the next startup of the game.
If you don't want spend the time and work
for this to be done, you can always cheat by taking a shortcut and burning a modified Eprom.So let's make an eprom that can be used to write the required byte to the NV-RAM...
There is three Versions in Mame, the parent set is "bubblem". The required rom are for the different versions:
Japan Ver. 2.3 (Rom: e21-10.19)
Overseas Ver 2.4 (Rom: e21-20.19)
America 2.5 (Rom: e21-16.19)
The offset that need to be modified is the same for all three versions. Load the rom into a hexeditor and change the value at the offset: $40E5D from $00 to $5A.
This offsett is the NV-RAM defaults. So when you have programmed the modified rom, just enter service mode and select "Factory Setting". Exit the service mode to confirm that
the title screen now displays "Extra Mode". After this you are done and can put back the original eprom again.
Good Luck
