This is the RAM map for Boktai 1 (U). Go to ROM map.

EWRAM

Address	Type	Description
0x020011c0	i32	Solar sensor: Calibrated level (0=dark, 140=max brightness. Calibrated level = calibration - raw level, then clamp to 0-140)
0x020011c2	i32	Solar sensor: Bars. Calculated from calibrated level (0=dark, 8=max brightness)
0x0203c800	u16[1024]	RNG table (generated by the bootstrap RNG once on power-on)
0x0203d800	byte[?]	#Stat struct
0x0203e000	byte[?]	Stat struct - backup (created on screen transitions, reloaded on death, saved to save file when saving)
0x0203e800	byte[?]	#World struct
0x0203ec00	byte[?]	World struct - backup
0x0203f000	byte[?]	#Scratch struct

Stat struct

Address	Type	Description
0x0203d80a	i16[7]	Grenade amounts
0x0203d88c	i16	Equipped lens
0x0203d88e	i16	Equipped frame
0x0203d892	i16	Equipped grenades
0x0203d892	i16	Equipped battery
0x0203d8b0	i32	Unlock Astro battery (must be set to `(0x03001c90 + 0x7dc)`)
0x0203d8f0	i16[3]	Django position
0x0203d91e	i32	Solar sensor: Calibrated level (see 0x020011c0)
0x0203dc18	i16	Item inventory size
0x0203dc1a	i16[42]	Item inventory IDs
0x0203dc6e	i16[42]	Item inventory amounts
0x0203dcc4	i32	Lens inventory (bitmask, 1 bit per lens and level)
0x0203dcc8	i32	Frame inventory (bitmask)
0x0203dcd0	i32	Battery inventory (bitmask)
0x0203dcd8	i16[8]	Lens EXP

World struct

Address	Type	Description
0x0203e8c5:6	bit[64]	"Chest opened" flags for current area (resets on area change)

Scratch struct

Address	Type	Description
0x0203f1b4	u8[13]	Carmilla: Pattern list - one of 4 hardcoded lists will be chosen at random when starting the fight
0x0203f1c1	u8[3]	Carmilla: Pattern pool (indices into pattern list)
0x0203f1c4	u8[3]	Carmilla: ???
0x0203f1c7	u8	Carmilla: Next pool value
0x0203f1c8	u8	Carmilla: Pattern index (index into pattern pool) - the (current/next?) pattern is pattern_list[pattern_pool[next_pool_value]]

IWRAM

Address	Type	Description
0x03000630	i32	Solar sensor interface: State (0=measuring, 1=resetting, 2=idle)
0x03000634	i32	Solar sensor interface: Counter (0-511, counts half-cycles of the 74LV4040 counter chip)
0x0300063c	i32	Solar sensor interface: shift out (next value to be written to GPIO_DATA)
0x03000648	void*	Script directory: Script index pointer
0x03000648	void*	Script directory: Script count
0x03000108	treasure_data*	Pointer to this map's #Treasure data (NULL if map has no treasures)
0x03001c2c	i16	Solar sensor: Bars. See 0x020011c2.
0x03001c90	void*	Pointer to Django's actor data?
0x03001cc8	void*	Pointer to linked list of bat enemies?
0x03004478	i32	Bootstrap RNG seed
+ 0x18	i32	Current lens level
+ 0x7dc	i32	Astro battery unlock password
0x030044f8	i32	Solar sensor interface: Is enabled (true/false)
0x030044fc	i32	Solar sensor interface: Last result (GPIO_DATA & 8)
0x03004508	i32	Solar sensor interface: Raw level (counter / 2 when GPIO_DATA & 8 becomes nonzero. 0=max brightness, 255=dark)
0x03004520	void*	Bytecode: Program counter
0x03004524	void*	Bytecode: Return value
0x0300450c	i32	Solar sensor interface: Timer interval (TM3CNT_LO will be set to -this value)
0x03004610	struct*	Pointer to current Map file descriptor (usually/always 0x02000010)
+ 0x00	i32	Number of Zones
+ 0x04	void*	Pointer to map file tile data
+ 0x0c	void*	Pointer to map file zones
+ 0x10	void*	Pointer to map file unknown block 1
+ 0x14	void*	Pointer to map file unknown block 2
+ 0x24	zone_callback[]	List of zone callbacks: struct zone_callback { /* offset 0x08 / u16 zone_id; / offset 0x24 / void bytecode_ptr; // Generally points into a Script };
0x03004620	i32	RNG index
0x030046a8	struct*	Pointer to #Save data header (usually/always? 0x03000768)
0x030046c4	struct*	Pointer to #Global save data (always 0x03000750)
0x030046e8	i16[3]	Camera position

Save data header

Offset	Type	Description
0x2c	char[?]	Player name

Global save data

Offset	Type	Description
0x00	i32	Global frame counter
0x04	i32	Solar sensor calibration (`raw level - 2` at time of calibration)

Other structs

Treasure data

// pointer to this struct is at 0x03000108
struct treasure_data {
  /* offset 0x24 */ treasure_node* list_head;
};

struct treasure_node {
  /* offset 0x14 */ treasure_trigger* trigger;
  /* offset 0x28 */ u32 callback_script_id;
  /* offset 0x2c */ u32 callback_args[?];
  /* offset 0xb8 */ treasure_node* list_next;
};

struct treasure_trigger {
  /* offset 0x20 */ i16 position[3];
};

EEPROM

Byte address	Byte size	Description
0x0000	0x18	#Global save data
0x00c0	0x28	Slot 1: #Save data header
0x0200	0x28	Slot 2: #Save data header
0x0340	0x400	Slot 1: #World struct
0x0780	0x418	Slot 1: #Stat struct
0x0dc0	0x400	Slot 2: #World struct
0x1200	0x418	Slot 2: #Stat struct
0x1840	0x168
0x1a40	0x168

Each block is followed by its checksum, see Save data checksums.