ePSXe (enhanced PSX emulator) is a PlayStation video game console emulator for x86-based PC hardware with Microsoft Windows or Linux, as well as devices running Android. It was written by three authors, using the aliases calb, _Demo_ and Galtor. ePSXe is closed source with the exception of the application programming interface (API) for its plug-ins.
As with many modern emulators, ePSXe makes use of plug-ins to emulate GPU, SPU (sound), and CD-ROM drive functions, a model first established in PSEmu Pro. Games can be loaded from the computer's CD drive or from one of many types of CD images directly from the user's hard drive.
A patching feature allows the user to apply game patches. Games that do not necessarily run properly, or even start at all, can be fixed and played via the use of ePSXe patch files in .ppf format. Not all games prone to bugs have ppf patches written for them.
Until version 1.9.25, ePSXe could only function with an image of an official Sony PlayStation BIOS. Since the various PlayStation BIOS images are copyrighted by Sony, it is illegal to distribute them. For this reason, ePSXe does not come bundled with any of the PlayStation BIOS images, requiring the user to provide one for the emulator. Version 1.9.25 added HLE BIOS support, allowing it to mimic the effect of the PlayStation's BIOS, although compatibility is currently lower than an official BIOS.
GPU: Most GPU plug-ins run with either Direct3D, OpenGL, or the Glide API, and are available as freeware or open source. Many GPU plugins require game-specific hacks to run games.
SPU: The SPU plug-ins can emulate everything from music to sound effects, with varying degrees of success depending on the plug-in settings, and of course the plug-in being used
CD-ROM: ePSXe comes with a core CD-ROM plug-in, but many others are available for freeware download and many can emulate up to seven different types of read modes
Input: The core plug-in is sufficient, but there are others that allow for more functionality.