Well, it's like this:
Japan: PC Engine = US: TurboGrafx
And here's the kind of Software you'll find:
PC Engine (JPN) Hucards: Work only with PC-Engine and Supergrafx
Turbografx 16 (US) Hucards/turbochips: Work only with the Turbografx/duo
Supergrafx (JPN) Hucards: Work only with the Supergrafx system
CD's (JPN/US): Most work on PC Engine and Turbografx CD/duo systems
SCD's/Super CD's (JPN/US): Most work on both PC EngineDUO/TurboDUO or
PCEngineCD/Turbobgrafx CD with system upgrade card.
ACD's/Arcade CD's: Require the Arcade Card (there's one for the PCEncgine CD,
and for the PCengineDUO). JPN only.
As far as CD rom Games go, a TURBODuo will pretty much cover all of them,
except for the ACD's. As for the HUCARD's, unless you find a convertor
(which are tough to find these days), you're going to need to get the DUO
modded up so that it can play both JPN and US.
The Supergrafx was a system NEC put out to compete with the SuperFamicom/NES.
It played Supergrafx games, as well as PCENGINE games. The system proved to
be pointless, though, and there are only a handfull of (overpriced) games
available for it.
As for the ACD games, you're only missing out on some lackluster Fatal Fury
ports and a crappy version of Strider.
As far as PCengine games go, well, basicly, there's about 700+ available. As
for the Turbografx, I think it's under 100 (am I correct?).
I think that covers it. I haven't had my TURBODUO modded yet, but I used to
have a PCEngineDuo, and believe me, I'd take being able to play the PC-Engine
Hucards over the TG16 games I've got collecting dust over in the corner here
any day of the week. Man, for the most part, the western world totally got
scammed.....TV Sports HOCKEY? What the hell is with this game?
Um, I haven't slept in 40 hours, so, I guess everyone else can just fill in
the gaps...