PCSX-Reloaded is an enhancement-focused, plugin-based PSX emulator.
It's the best choice if you want to play 3D games at resolutions bigger than native. If you encounter glitches or it's a 2D game, use Mednafen instead.
The stable release is very old, so use the latest SVN build instead.
Check Recommended PSX Plugins for plugin configuration.
Changing discs with PCSX-R
Some games (like Final Fantasy) allow you to save in the "Disc Change screen". For games that don't allow that (like Metal Gear Solid), disc switching can be a bit tricky:
- Press F9 to open Disc tray
- Press Esc to go to PCSX-R menu
- Emulator → Switch ISO...
- Emulator → Run
- Press F10 to close Disc tray