The SEGA Dreamcast, in many ways, was like the movie The Blues Brothers. Both highly awesome, both incredibly underrated and both never fully appreciated until after their appointed time.
Instead of using CD-ROMs like most of the previous generation relied on, The Dreamcast utilised GD-ROM disks. These were proprietary optical disks developed by Yamaha that had a capacity of 1.2 gigabytes, which was fairly impressive at the time as the DVD was only in its infancy around 1998. More on that in a second though.