>which language is required for programming plugins and all that
>stuff ?
Given that most of the Plugins we deal with conform to a specification, you can most likely write a plug-in in any language you'd like so long as it provides an interface to the calling application. The source that Pete provides for the one plug-in is in C++.
>I wanna know how an emulator can be programmed ?
As for how emulators come to be, it's always been my belief that the authors of an emu get whatever input a console provides, determine just what the info is, and act accordingly. Seeing as how a few console companies provide standards documents regarding the games that play on their systems, this task can be simplified (but I'm fairly certain only the official devlopers get the SDK with such information).