Can anyone in here atually tell me the differences in the arcade cards (HuCards) for the duo and cd systems? I know that they let you play some of the more demanding games, but are they basically like the ram cart for the saturn and such?
Apparently, the Arcade Card for the original CD-ROM system has 18 megabits of RAM, and the Arcade Card Duo has 16 megabits of RAM (but the Super CD System / Duo has 2Megabits more, so the total is the same). I've also heard that there was onboard addressing hardware that was used for fast multiply/divide operations.
The CD System cards essentially contain the BIOS for the CD system (I'm not sure, but I guess this would have to be duplicated on the Arcade Card Pro as well). AFAIK, they're only necessary for a PC-Engine/TG16 with the original CD-ROM add-on, as the Super CD-ROM add-on and Duo have a version 3 BIOS built in.
You can also use the Arcade Card Pro on your Turbo Duo, just incase you are wondering. I was surprised how well the Neo-Geo games look on the Duo, Fatal Fury Special for the Arcade Card blows away the Sega CD's version.