

Unlike HuCards, PC Engine CD-ROMs are not region locked, and therefore will function on their TurboGrafx-16 equivalent units and vice versa.

Theoretically all CD-ROM² systems can run software of all three formats, however some require "system cards" to enable this functionality.

The complex nature of the CD-ROM² line has led to NEC Retro grouping all CD-based PC Engine variants under the same umbrella term. These CD-ROM² systems, beginning with the appropriately titled CD-ROM² would take a number of forms over the coming years, complementing the base system and its range of games on HuCard. In December 1988 NEC Home Electronics began to release video games on CD-ROM for its PC Engine console.
