The TurboDuo (also called Turbo Duo) was a video game console released in the United States on October 10, 1992 by Turbo Technologies Incorporated, a Los Angeles-based corporation consisting of NEC and Hudson Soft employees, established to market NEC consoles in North America after NEC Home Electronics USA failed to effectively market the platform. The Duo was codeveloped by Hudson Soft and NEC. The Japanese counterpart was the PC Engine Duo game console, which was released over a year earlier.
The TurboDuo is essentially a combination of TurboGrafx-16 and TurboGrafx-CD hardware, plus the Super System BIOS + extra 192k RAM built-in to the motherboard. The TurboDuo was capable of playing standard audio CDs, CD+Gs, TurboGrafx TurboChips, Japanese and North American CD-ROM² (TurboGrafx-CD) and Super CD-ROM² titles. The system is able to play Japanese PC Engine HuCARDs with a third party HuCARD converter or modification. With a HuCARD converter plus a Japanese Arcade Card Duo, the system can also play Japanese Arcade CD-ROM² games.
TurboChip is simply the North American term for HuCARD.
Source: Wikipedia, "Turbo Duo", available under the CC-BY-SA License.