Mysteries

2026-03-22T12:05:21Z

Stopa: /* Is there more than one revision of the bootrom? */

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 [http://problemkaputt.de/twl-core.jpg DSi SoC pinout] shows evidence of dual NTRCARD controllers on the final DSi SoC. (This was a [http://i.imgur.com/0kJlbEw.png 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 a JTAG? ===
=== 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, iQue3DSXL), 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 did SVC 0x74 in the ARM11 kernel do before it got stubbed? ===
=== 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
=== Why are there 4 stubbed syscalls named SendSyncRequest1-4? ===
=== 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.

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Mysteries