Dreamcast:Creating Game Backups

Premises

 * The Dreamcast uses 3 main sections. The first 2 are readable by most CD Drives, and usually contain a warning about not using it on a CD player, and sometimes bonus content, including images, text, and audio. This section is 4 minutes long, or around 35 MB.
 * The next section usually only contains copyright information, typically "Produced by or under license from Sega Enterprises LTD Trademark Sega"
 * The main data section is not readable by most CD players, as it is empty according to the CD table of contents. It is a 1.0GB large, higher density partition, used for game data. Some drives can be modified to ignore this, and read from the main partition.
 * Most GD-ROMs use GDI format, which contains some headers. All GD-ROMs are at least 3 tracks long, with the data track closest to the end being game data.
 * On GD-ROMs with audio tracks, track 3 will be the header for audio, followed by the audio tracks, with the last track being the file data.
 * GD-ROMs are proprietary and practically unused aside from the Dreamcast and its associated arcade platforms.
 * The last track included a program labelled "IP.BIN" by the community, which displayed the license screen and ran the bootstrap to start the game executable. The filename of the game executable is usually "1ST_READ.BIN".
 * Most games do not use the whole 1GB of space available.

Copy protections

 * As GD-ROMs could only be made by Sega, the copy protection seemed unbeatable at first. There was no way to extract the game from the higher-density data partition with a normal CD Drive, and there was no way to write data back so the Dreamcast would read it as game data.
 * However, Sega, while making the Dreamcast, wanted it to be able to play CD Media, and thus allowed the Dreamcast to read MIL-CDs, a way to add multimedia functions to music CDs, including navigational menus, internet access, and video. There were very few of these ever made, and they were only ever released in Japan.
 * When reading a MIL-CD, to prevent them being used for game backups, Sega made them load IP.BIN normally, but scramble 1ST_READ.BIN so the executable would crash immediately.
 * In late 1999, a hacking group (Utopia) stole a Katana Devkit and dumped the "unscrambler" program, which allowed game data to be properly read from a CD-ROM, defeating the copy protections and allowing game backups to be ran, as well as allowing homebrew to be ran which allows for the dumping of games, originally through the Dreamcast serial port.
 * Sega later released a second revision of the Dreamcast disallowing loading of MIL-CDs and therefore making homebrew and running backups impossible without replacing the BIOS chip or adding an ODE.

Redump's Disc Image Creator
Redump, which aims to be the ultimate collaborative reference of disc images, provides a comprehensive tool to do so; however, for the above reasons, few optical drives are compatible with it, and those that are usually need to be modified to be able to read and copy a GD-ROM.

Dumping from the Dreamcast
An exploited Dreamcast can dump GD-ROMs over the Broadband/LAN adapter, a Serial SD Card adapter, or an IDE/CF drive, using Dreamshell.

Broadband/LAN Adapter
Using httpd-ack, you can dump Dreamcast games assuming you have a way to connect the Dreamcast to your network. It can only dump one track at a time, so there are scripts available to ease the process of dumping multi-track discs. It is also very slow, usually around 40KB/s.

Serial to SD adapter
Using a standard Dreamcast Serial to SD card adapter, you can dump GD-ROMs, assuming you can boot homebrew. This is a fairly easy solution, only requiring buying the adapter and burning the CDI. The speeds averages out to about 650KB/s, meaning many GD-ROMs will be dumped in around 30-35 minutes.