Mil-CD is a specially formatted CD-ROM that is designed to automatically boot a Dreamcast-compatible program without the need for a GD-ROM. Sega officially used Mil-CDs for Dreamcast-enhanced audio CDs.
bleem! first showcased the ability to load independent software on the Dreamcast at E3 2000. Gameshark used the Mil-CD technique to load it's game cheat program on the Dreamcast, which it released on June 2, 2000. On June 20, 2000, Marcus Comstedt reverse engineered the Gameshark CDX and released his findings on his internet homepage.