|Source code||Google Code (leaked)|
UltraHLE is a discontinued freeware Nintendo 64 emulator which gained notoriety for being the first to run commercial games at full speed on the hardware of the time.
The Nintendo 64 was only about three years old at the time of UltraHLE's release. While there were earlier projects aiming to emulate the console's inner workings, UltraHLE was the first to run games at playable speed on a typical Pentium II/III system with a decent GPU. While emulators for earlier systems concentrated on simulating operations at a lower level (although they too, like NESticle and ZSNES, resort to game-specific hacks and other shortcuts for games to be playable on modest hardware), co-authors Epsilon and RealityMan took a different approach through intercepting C calls and using libraries to respond to them. This also led to a strange situation, especially with later NES/SNES emulators, wherein emulating the Nintendo 64 would at the very least call for similar if not lower-end hardware compared to emulating an early console in an accurate fashion.
UltraHLE also used the Glide API, which has since fallen out of use due to being specific to 3dfx adapters. Due to its popularity, several Glide to DirectX translation utilities were made specifically for UltraHLE for non-3dfx video cards.
As it was released at the time when the console was still on the market and considered profitable, Nintendo threatened the authors with legal action. This, along with pressure from users who constantly pestered the developers for new features and such, led to Epsilon and RealityMan discontinuing the emulator.
Other than being of historical value and for the distinction of trolling Nintendo while they were still marketing the console, users are generally better off with newer emulators due to its limited compatibility and dependence on the Glide API.