Mysteries

The following is a list of mysteries.

General

• What is the CTR abbreviation?

C may stand for Chiheisen ("horizon" in Japanese, the O3DS's codename being "Project Horizon").

Not true, Horizon refers to the OS.

CTR stands for Citrus.

Hardware

Why are there two CTRCARD controllers?

Background: Also DSi SoC pinout shows evidence of dual NTRCARD controllers on the final DSi SoC. (This was a planned feature of the DSi before being axed later in development)

Why are there two EMMC controllers?

Theory: At some point during 3DS hardware development there was an idea to split up CTR and TWL nand into two different chips.

Is there more than one revision of the bootrom?

Background: Bootrom visible portion has been dumped on the entire 3DS Family (3DS, 3DSXL, 2DS, New3DS, New3DSXL, New2DSXL), and even a prototype board from April(?) 2010. All matching exactly.

What is the EMMC controller @ 0x10100000 doing?

Background: There's dead code in NWM referencing it.

Why did they put NTRCARD accessible from ARM11?

Theory: At some point during 3DS hardware development there was a concept where ARM11 ran a menu with DS(i) icons while ARM9 was in TWL mode.

Is there a secret message embedded in the 3DS keyscrambler constant?

Background: TWL key scrambler constant was "Nintendo Co., Ltd" in Japanese ("任天堂株式会社"), UTF-16LE encoded, with byte order mark. The 3DS key scrambler constant, by comparison, is random-looking.

What is the PDN abbreviation?

PowerDowN

How does Nintendo reflash bricked systems?

Before trying to boot from NAND, the bootrom checks to see if a key combination (Start + Select + X) is being held, and whether the shell is closed. If so, it tries to boot from an inserted NTR (Nintendo DS) cartridge. This allows to execute a FIRM that is probably used by Nintendo to reflash the system.

Software

What was the problem in "initial program loader" that was mentioned in an FCC filing by Nintendo for 2DS?

Background: http://www.neogaf.com/forum/showthread.php?t=814624&page=1

This could be referring to the ROM on the AR6K wireless chip:

• Some 2DS units have the WiFi chip soldered directly to the board (such as the 2DS in this FCC filing: https://fccid.link/BKE/FTR001N), and some do not.
• The AR6K ROM only acts as an initial loader.
• Maybe some AR6K-family devices allow signature checks on the firmware? Or maybe some registers weren't write-once but should have been?

What is the PTM abbreviation?

PlayTime Management

Why is the DTCM not used anywhere except bootrom?

Background: Bootrom is known to use part of DTCM as state, memsetting it to 0 when it's done. After that, it is never used again.

How is CTRAging launched during factory setup?

Background: No TestMenu version is capable of launching CTRAging directly: O3DS factory TestMenu can only launch DevMenu installed on NAND, the inserted cartridge and the TWL/AGB test apps; N3DS factory TestMenu can only launch DevMenu installed on NAND, the inserted cartridge and System Settings.

Theory: NtrBoot another time

Is there a deterministic formula for calculating the Movable.sed KeyY high u64?

Background: We know now that the high 4 bytes of KeyY can be reliably estimated to be 1/5th of the LocalFriendCodeSeed (low 8 bytes of KeyY), which is close enough to brute force. However, the actual value is usually about 0-4000 units off the actual high u32 of the KeyY (called msed3 in the seedminer implementation). Could there possibly be a deterministic formula given this 1/5 ratio is so close to the correct value? It's difficult to imagine this is just a coincidence.