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.

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 a JTAG?

Is there more than one revision of the bootrom?

Background: Bootrom visible portion has been dumped on 3DS, 3DSXL, 2DS, New3DS. 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?

Power distribution network

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

What did SVC 0x74 in the ARM11 kernel do before it got stubbed?

What is the PTM abbreviation?

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.