NAND Memory Layout

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Revision as of 18:12, 3 January 2015 by Vogtinator (talk | contribs) (Minor mistake fixed)
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NAND Flash

NAND pages are 528-bytes long (512 + 16-bytes header) on TI-Nspire and 2112-bytes long (2048 + 64-bytes header) on TI-Nspire CX/CM.

  • pages 0000 to 001F (Nspire) or 0000 to 003F (CX/CM): written to /phoenix/manuf.dat at each boot
    • Offset 000-003: 3C B0 6E 79
    • Offset 804-805: model ID (in little-endian): 0C (Nspire CAS), 0D (Nspire Lab Cradle), 0E (Nspire), 0F (Nspire CX CAS), 10 (Nspire CX), 11 (Nspire CM CAS), 12 (Nspire CM)
    • Offset 806-807: unknown - 00 00 or 10 00
    • Offset 808-80F: optional default language (CX/CM), filled with FF if missing - ISO 639 supported language string padded with 00 (for exemple fr, en, ar, zh_CN for TI-Nspire CX-C or CM-C...)
    • Offset 818-81B: signature - 91 5F 9E 4C (CX/CM)
    • Offset 81C-81F: features - 05 00 00 00 (CX/CM)
    • Offset 820-823: default keypad - 4C 00 00 00 (CX/CM)
    • Offset 824-825: lcd width - 40 01 (CX/CM)
    • Offset 826-827: lcd height - F0 00 (CX/CM)
    • Offset 228-229: lcd bpp - 10 00 (CX/CM)
    • Offset 82A-82B: lcd color - 01 00 (CX/CM)
    • Offset 82C-82F: offset diags - 00 00 32 00 (CX/CM)
    • Offset 830-833: offset boot2 - 00 00 02 00 (CX/CM)
    • Offset 834-837: offset boot data - 00 00 2C 00 (CX/CM)
    • Offset 838-83B: offset file system - 00 00 40 00 (CX/CM)
    • Offset 83C-83F: config clock - 02 10 56 00 (CX/CM)
    • Offset 840-843: SDRAM config: 12 80 01 FC for 64MB (CX) or 11 80 01 FE for 32MB (CM)
    • Offset 844-847: lcd spi count - 02 00 00 00 (CX/CM)
    • Offset 848-887: lcd spi data filled with 0xFF - 06 00 00 00 5C 00 00 00 30 00 00 00 04 00 00 00 (CX/CM)
    • Offset 888-889: lcd light min - 1A 01 (CX/CM)
    • Offset 88A-88B: lcd light max - CE 01 (CX/CM)
    • Offset 88C-88D: lcd light default - 6A 01 (CX/CM)
    • Offset 88E-88F: lcd light increment - 14 00 (CX/CM)
    • Offset 890-893: 0C 01 A2 18 (CX/CM)
    • Offset 894-923: display informations on the 12 elements of the splash screen (CX/CM): horizontal display offset + vertical display offset + width + height (2-bytes each) + data offset (4-bytes)
      • Offset 894-89F: Low Battery error icon [diplayed unknown]
      • Offset 8A0-8AB: Boot1 Recoverable Error icon [displayed 8th]
      • Offset 8AC-8B7: Send Diagnostics Software info icon [displayed 8th]
      • Offset 8B8-8C3: Boot2 Recoverable Error icon [displayed 8th]
      • Offset 8C4-8CF: Unrecoverable Error icon [displayed 8th]
      • Offset 8D0-8DB: Progress Bar Background [displayed 6th]
      • Offset 8DC-8E7: Progress Bar [displayed 7th]
      • Offset 8E8-8F3: permanent element #1 (background) [displayed 1st]
      • Offset 8F4-8FF: permanent element #2 (unused) [displayed 2nd]
      • Offset 900-90B: permanent element #3 (unused) [displayed 3th]
      • Offset 90C-917: permanent element #4 (unused) [displayed 4th]
      • Offset 918-923: permanent element #5 (unused) [displayed 5th]
    • Offset 924-927: compressed splash screen data size
    • Offset 928-92B: uncompressed splash screen data size
    • Offset 930-???: compressed splash screen data (same compression format as the boot2)
  • pages 0020 to 0A7F (Nspire) or 0040 to 057F (CX/CM): boot2 image
  • pages 0A80 to 0AFF (Nspire) or 0580 to 063F (CX/CM): "bootdata" (every time this is modified, the next available page is used; if all 128 pages are in use, then the whole area is erased first)
    • Offset 00-03: Marker AA C6 8C 92
    • Offset 04-07: Downgrade protection: minimum OS version allowed as a 4-bytes word (major-minor-lower1-lower2). Written during OS installation with the value found in the second field 8020 of the OS upgrade file
    • Offset 08-0F: Seems to hold the press-to-test status (word, word, long word)
    • Offset 10-13: If nonzero, BOOT1 will attempt to run DIAGS by default; if zero, it will skip straight to BOOT2. (Either behavior can be overridden with the Esc+Menu+G key combination.)
    • Offset 14-1A: TI-84 Plus emulator 0A1 certificate field
    • Offset 1B-1E: TI-84 Plus emulator 041 certificate field
    • Offset 1F-61: TI-84 Plus emulator 0A2 certificate field
    • Offset 64-67: (OS 1.6+) Default LCD contrast (if not in range from 0x76 to 0x8A, assumed to be 0x80)
  • pages 0B00 to 0F7F (Nspire) or 0640 to 079F (CX) or 0640 to 7BF (CM): diags software
  • pages 0F80 to 0FFF (Nspire) or 07A0 to 07FF (CX): diags test results
  • pages from 1000 (Nspire) or 0800 (CX) or 07C0 (CM): factory images or filesystem

Factory images

At startup, boot2 checks the NAND flash for a pre-loaded factory image. The format is a 32-byte header followed by the .tnc/.tno file contents:

  • Offset 00-13: String "***PRELOAD_IMAGE***"
  • Offset 14-17: 55 F0 01 55
  • Offset 18-1B: (unknown)
  • Offset 1C-1F: Size of image (in big-endian)

If boot2 finds this header, the user is prompted to press 'I' on the keypad. After that, the image is copied to RAM before creating the filesystem (The filesystem also starts at page 0x1000, so it cannot co-exist with a factory image), and is installed the same as if it had been received from the serial port.

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