NAND

The DSi uses a 256MB Samsung moviNAND flash chip, which is a NAND flash chip with a built-in controller that implements a MMC (SDIO) interface. In many ways, it's like an SD card in BGA packaging, and some people have successfully read it with modified SD card readers. The last 16MB is used for wear-leveling purposes (such as replacing bad blocks), while the first 240MB is used for storing actual data.

Addressing is done in terms of 512-bytes sectors. All wear-levelling and bad-block-mapping is handled transparently inside the chip by the controller. Most sectors are encrypted with a per-console key.

Layout:

Offset	Size	Description
0	0x200	PC-style Master Boot Record (MBR), encrypted with a per-console key
0x200	0x200	Stage 2 info block 1 (see stage2)
0x400	0x200	Stage 2 info block 2
0x600	0x200	Stage 2 info block 3
0x800	0x4DC00	Stage 2 bootloader (encrypted with a universal key)
0x4E400	0x400	Stage 2 footer -- unknown format, but first 10 bytes are build number of Stage 2 bootloader
0x4E800	?	Unused (all 00)
0xffa00	0x400	Diagnostic area. (often contains build date of device in plaintext) Blank in never-before-booted DSi. Might be written to during firmware updates.
0x10ee00	?	First sector of main FAT32 partition
0xcf09a00	?	First sector of photo FAT32 partition