So... if I understand correctly it goes something like this.
A PC Engine Duo with an Arcade Card Duo can play Arcade CDs.
The Arcade Card Pro is basically a 3.0 system card and the Duo card combined to allow a PC Engine + CD to play Arcade CDs.
Correct?
I ask this because I just picked up a Duo-R and an Arcade Card Duo, but the start up screen still says "Super CD-ROM2 version 3.00" and Arcade CDs won't play. Does this just mean that my Arcade Card Duo doesn't work or needs to be cleaned? Other HuCard games work on the system, so it is not an issue with the slot. So far the only Arcade CD I have to test this with is Fatal Fury Special, but I've also ordered Fatal Fury 2, Art of Fighting, and World Heroes 2 and they just haven't arrived yet.
On an unrelated note, I'd really like to find Sapphire and Strider Hiryu, but there wasn't a single copy of either on Ebay when I looked. Seeing as there are only 12 Arcade CDs I've considered just trying to get all of them.