GD-ROM

From GamerWiki

A proprietary format, created by Hitachi and based around the CD-ROM format, that can hold up to one gigabyte of data and this capacity is the reasoning behind the name: Gigabyte Disc-Read Only Memory.

GD-ROMs were used only by the Sega Dreamcast and Sega Naomi arcade boards.

Information on a GD-ROM is stored in three sections; a track containing regular CD data, a separator (containing a printed copyright notice) and the final, compressed track. Compression of this track is achieved by slowing the speed of the disc, allowing regular CD-ROM parts to read the disc; cheaper for Sega to produce, using 'off-the-shelf' parts in the Dreamcast.

Despite the use of a proprietary GD-ROM format, a debug function left in by Sega in the BIOS meant the system could boot specially burnt CD-R. This meant that, due to the proliferation of CD writing hardware for PC systems, Dreamcast piracy was rife. Few, if any, titles used the full capacity of the GD-ROM format in a way that prevented software from being copied and many titles that were too big were downsized to fit on a single CD-R. The ability of the Dreamcast also meant it was the first system to receive the full support of the Home-brew community.

The addition of a Modchip to the Dreamcast console meant that it was possible play imported games without disc-swapping, however, uniquely, it did not aide in playing pirate games. Because of this modchipping Dreamcasts is considered much more legitimate and SEGA did not actively prosecute modchip sellers and manufacturers.