NCSD

This page documents the format of NCSD.

Overview

There are two known specialisations of the NCSD container format. The CTR Cart Image (CCI) format and the CTR System Update (CSU). CCI is the format of retail game ROM dumps. CSU is used with developer system updates and tools

NCSD images start with a NCSD header, followed by up to a maximum of 8 NCCH partitions. The first partition(NCCH 0) usually starts at 0x4000, this is generally the main NCCH (Executable). The following info on partitions 1, 2, and 7 are only valid for .CCI. The second partition(NCCH 1) contains the game "Manual"(title ID for the .CFA containing the Manual always starts with '0005'). The third partition(NCCH 2) contains the download play "Child"(The title ID for the .CFA containing the DLP Child always starts with '0006'). The eighth block(NCCH 7) contains "Update Data"(The title ID for the .CFA containing the Update Data always starts with '8000') The format of partitions can be determined from the partition FS flags, while the contents can be determined from the partitions flags.

NCSD header

Offset	Size	Description
0x000	0x100	RSA-2048 SHA-256 signature of the NCSD header
0x100	4	Magic Number 'NCSD'
0x104	4	Size of the NCSD image, in media units (1 media unit = 0x200 bytes)
0x108	8	Title/Program ID
0x110	8	Partitions FS type
0x118	8	Partitions crypt type
0x120	0x40=(4+4)*8	Offset & Length partition table
0x160	0x20	Exheader SHA-256 hash
0x180	0x4	Additional header size
0x184	0x4	Sector zero offset
0x188	8	Partition Flags: byte[5]-byte[7] indicate content type ( system update, application, manual, ... ) size of media units ( 512*2^byte[6] ) and encryption.
0x190	0x40=8*8	Partitions' Title ID table
0x1D0	0x28	Reserved
0x1F8	8	Unknown
0x200	4	Always 0xFFFFFFFF
0x204	252	Padding?
0x300	4	Used ROM size in bytes
0x304	28	Padding
0x320	8	NVer Title ID (Only Present in retail .CCI)
0x328	8	NVer Title Version (Only Present in retail .CCI)

Parts of the first NCCH block's header are found around 0x1000 for whatever reason. NCSD can hold up to 8 partitions. (i.e. Mario Kart 7 holds 4 NCCHs, most we've seen so far)

The region-specific NVer title for this NCSD presumably must exist on NAND. The NVer title version may also be used to check whether a system update is required before running the app.