Naomi CF boot

The NAOMI (including Chihiro and Triforce) Compact Flash solution is a 'drop in' replacement for the GD-ROM system. The setup includes:

• Compact Flash reader unit (Sega Japan made, with common SCSI style interface connector and 5 pin GD-ROM power header)
• Firmware update GD-ROM (specific to system for included game only)
• Security PIC
• Compact Flash card with encrypted game image (manufactured by Hagiwara Sys-Com)

The solution appears to be exclusive the UK.

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The following is copy/pasted, unconfirmed, and believed to be incomplete, but probably a nice starting point.

1. Read ATA IDENTIFY DEVICE data.
2. Read 2 bytes of the CF serial number (offset +0x24 in the identify structure). [This means games are locked to a specific card, i.e. copying data from one official Sega card to another official Sega card most likely won't work, unless by extreme coincidence the 2 bytes read have identical values.]
3. Use these 2 bytes as a word, and add 0x20 to the value. This resulting value will give the location of the xor "key" data sector.
4. Go to that sector, and xor this data (byte by byte) with the data in encrypted sector 0x277.
5. Use the same two bytes of the serial number as above as a word, but this time add 0x19.
6. Go to that sector, compute a sum of 16-bit words, accumulating in a 32-bit dword.
7. This value must match the 32-bit dword stored at offset 0x38 in sector 0x1D7.
8. The 8-byte manufacturer ID must match a specific value. [Hagiwara Sys-Com cards only.]