The Wayback Machine - https://web.archive.org/web/20080218151806/http://mc.pp.se:80/dc/gdrom.html
The GD-ROM (GD for "GigaDisk", referring to the capacity of approx. 1
GB) drive is custom made for SEGA by Yamaha. It uses a regular CD-ROM
laser (as opposed to a DVD drive which uses a different wavelength),
but has the necessary firmware to access data stored in the
proprietary GD-ROM format, which packs the bits more densely than on a
normal Yellow Book CD.
A GD-ROM disk actually consits of two data regions, separated by a
data-less separator ring. The inner region contains a normal Yellow
Book CD-ROM track, and a Red Book CD-DA track. This region can be
read in any CD drive. The outer region (outside the separator ring)
is the high-density area which contains the actual game data (both
files and CD-DA audio).
What little information is known about the GD-ROMs originate mainly
from this Powerpoint presentation made by SEGA techs:
Dreamcast Programming by Marcus Comstedt
Last modified: Thu Jun 22 01:48:38 MEST 2000
