WonderWitch/Memory map

The following documents the WonderWitch memory map. Note that you are not required to follow these rules to the letter; however, some amount of the beginning of memory is expected to be left to FreyaBIOS, FreyaOS, etc.

Internal RAM (0x00000 - 0x0FFFF)

WonderWitch memory map

Address	ASCII, 1 screen	ASCII, 2 screens	Shift-JIS, 1 screen	Shift-JIS, 2 screens
0x0000	Interrupt vectors
0x0100	Internal BIOS area
0x0290	Stack, user IRAM	Stack, user IRAM	Stack, user IRAM	Stack, User IRAM
0x0E00				Sprite table
0x1000				Screen 1
0x1600			Sprite table
0x1800			Screen 1	Screen 2
0x2000			Tile data (512 tiles)
0x2600		Sprite table
0x2800		Screen 2
0x2E00	Sprite table
0x3000	Screen 1
0x3800	Tile data (128 tiles)
0x4000	Color tile data; only restored with ResumeIL.
0xC000	Unused; never restored on program suspend/resume.
0xFE00	Color palette data; only restored with ResumeIL.

In all modes, the stack is placed immediately before the sprite table.

Note that the user IRAM area is shared between all users of FreyaBIOS - notably, FreyaOS puts

Interrupt vectors

Start	End	Description
0x00	0x07	CPU interrupts
0x08	0x0F
0x10	0x18	FreyaBIOS interrupts
0x19	0x27
0x28	0x2F	SoC interrupts

Internal BIOS area

Start	Length	Description
0x100	128	Temporary memory buffer. Used for XMODEM transfers by FreyaOS.
0x180	64	Wavetable memory location.
0x204	2/4?	Written to by FreyaOS using sys_alloc_iram to point to its IRAM area.
0x230	2	Near pointer to temporary memory buffer (0x0100).

Cartridge SRAM (0x10000 - 0x1FFFF)

Bank	Description
0	/ram0 file data
1	Third process data
2	Second process data
3	First process data; typically used by FreyaOS

Cartridge flash (0x80000 - 0xFFFFF)

The 512KB of NOR flash memory is mapped and partitioned as follows:

Linear address	Size	Description
0x8nnnn	384 KB	/rom0 file data
0x9nnnn
0xAnnnn
0xBnnnn
0xCnnnn
0xDnnnn
0xEnnnn	64 KB	FreyaOS
0xFnnnn	64 KB	FreyaBIOS