The initial base of the current emulator, PCSX, was first released for the PC on August 31, 2000. It has a completely reworked and modernized GTK2/Glade GUI, integrated plugins, an improved system for classic PSEmu plugins, better configuration tools, support for translation, easy installation, and support for AMD64. The old PCSX-df branch is a fork of the PCSX PlayStation emulator designed specifically for GNU/Linux (and probably other similar systems).
It was based on PCSX-df 1.9, with, in its early times, support for Windows, GNU/Linux and Mac OS X (at the time) as well as many bugfixes and improvements.
PCSX-Reloaded is a plugin-based PlayStation emulator created in mid-2009.