All emulators usually work, just ones today use things such as plugins and BIOS. The BIOS is required for the OS and region. Basically what runs the emulator. Without it, it will not function. Then once you got your Bios you need the plugins. The plugins are the tools that run your controller,
audio, video, memory, etc...
Emulators like Nintendo's are the same, just these are built directly into the emulator by whom made them. The Playstation 2 emulators are more open source so they use things such as plugins so other developers can improve upon them.
You must also take in consideration when emulating hardware through software. Your system specifications are a lot higher needed then what the actual hardware itself requires. This is because you are emulating it. PS2 emulators require a pretty fast computer to even run at a low framerate. If
you for example can barely run Endless Online. You will never be able to run a PS2 emulator or even a PS1.
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"Everyone is a retard until they prove themselves otherwise."