Dr. Robotnik's Mean Bean Machine/Technical information

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Locations

This is an highly incomplete list of locations in the ROM, mainly about the sound driver and music-related stuff.

Offset	Description
$18BA - $2791	Bytecode
$B0000 - $E7FFF	PCM samples. Split in banks of $8000 bytes to work with the Z80, padded with $FF.
$E8000 - $EFFFF	DAC samples. Padded with $FF.
$F6000	Sound driver (Cube/Iwadare). Z80 code.
$F8000	Voices used in the songs, arranged in groups of $1D bytes each.
$F937C	Song data, in the Cube/Iwadare format.

Bytecode

The game uses bytecode for the general main loop rather than just using 68000 code. This is also present in the original Puyo Puyo and subsequent ports. Here are the instructions:

$00	Stops executing the bytecode. Execution is to be resumed by other code.
$01	NOP (I think)
$02	Delay for a number of frames
$03	Waits for a palette fade to finish
$04	Stores a word sized value into RAM
$05	Calls a 68000 routine
$06	Equivalent to BRA
$07	Equivalent to BEQ
$08	Equivalent to BNE
$09	Using what's stored in the bytecode's flag, it branches to an address from a table
$0A	Initializes VDP registers from an ID (the game uses different sets of register data)
$0B	Decompresses "Puyo" art into VRAM
$0C	Call set of a VDP plane commands
$0D	Loads a palette into a palette line
$0E	Fades into a palette in a palette line
$0F	Play a sound
$10	Play a sound (checks if samples are allowed)
$11	Fade out music
$12	Stop all sounds
$13	Identical to $10
$14	Decompresses Nemesis art into VRAM
$15	Fades into a palette in a palette line (with a check for which stage intro that is used)
$16	Decompresses "Puyo" art into VRAM (with a check for which stage intro that is used)

RAM locations

Offset	Description
$FF0112	Stage ID
$FF0113	Opponent ID
$FF0134 - $FF0135	DMA disable flag
$FF05C6 - $FF05C7	Frame count (used for VSync)
$FF05D2 - $FF0621	Vertical scroll buffer
$FF0622 - $FF0A21	Horizontal scroll buffer
$FF0A22 - $FF0A35	VDP register values
$FF0A36 - $FF0A39	Bytecode PC
$FF0A3A	Flag used for bytecode, typically used in the bytecode for branching
$FF0A3B	Bytecode disable flag
$FF0A3C	Flag in which if set it runs the next instruction in bytecode without VSync
$FF0A3E - $FF0A56	Palette data
$FF0AD6 - $FF0C5B	Palette fade data
$FF0E86 - $FF1105	Sprite buffer
$FF110A - $FF110F	Player 1 controller data
$FF1110 - $FF1115	Player 2 controller data
$FF1116	Random number generator seed
$FF112A	Flag in which if set it will load Robotnik's lair as the level intro
$FF4100 - $FF42FF	Nemesis decompression buffer
$FF4300 - $FF4FFF	DMA queue
$FFE000 - $FFEFFF	Object RAM
$FFFC02	Flag that is set if the console is detected as non-Japanese
$FFFCA4	Number of game matches in 1P vs. 2P mode
$FFFCA6	Player 1 A button assignment
$FFFCA7	Player 1 B button assignment
$FFFCA8	Player 1 C button assignment
$FFFCA9	Player 2 A button assignment
$FFFCAA	Player 2 B button assignment
$FFFCAB	Player 2 C button assignment