PSEmu was a PlayStation emulator created by Duddie, Kazzuya and Tratax, the first versions of which were made for MS-DOS and the later for Microsoft Windows. The team that created it also helped in the development of Connectix Virtual Game Station.
PSEmu Pro was later discontinued, though its plugin system is still used by all major Playstation emulators today (excluding pSX emulator).
Early MS-DOS versions
The early MS-DOS versions were made exclusively by Duddie. The first version came out on June 4,1997. It was not able to run any commercial game, nor did it have any audio output code, but it included a debugger which allowed the user to inspect the sequence of assembly instructions that made up a Playstation executable.
Subsequent versions were able to display the menu from Raiden, but they were slow (they ran at 10% speed of "realtime" on a Pentium 200 with MMX) because the core of the emulator was a simple interpreter.
The last version for MS-DOS came out on January 13,1998.
On October 19,1997, work was started on a different version of the emulator (which would be known as PSEmu Pro) by Duddie, Kazzuya and Tratax. This version was released on August 31,1998: it only ran under Windows, but it was much faster and more compatible than the earlier MS-DOS versions (it allowed to run a number of commercial games at full speed on entry-level systems), because it emulated the Playstation CPU through dynamic recompilation and used an open plugin system to emulate the GPU, SPU, joypads and CD drive, which would allow any coder to write their own plugins for the emulator. By using a video plugin supporting 3D acceleration, the games could even look better on the emulator than on the real console, because they could be displayed at high resolutions and bilinear filtering could be applied on the textures (something the Playstation could not do). In addition, the emulator included a cheat code manager which typically could activate features like invincibility and infinite lives, but could also be used to improve compatibility with games like Gran Turismo.
New versions of PSEmu Pro with improved compatibility, and new plugins with better video and audio emulation, were regularly released up to February 1,1999, when the last version (1.0.21) was released.
PSEmu Pro was discontinued when a beta of version 2.0 was leaked, but most of the existing Playstation emulators still use its standard for plugins. This does not only mean that other Playstation emulators can use plugins that were originally written for PSEmu Pro, but PSemuPro itself can correctly use plugins that were written for other emulators after it was discontinued.
On January 6,2000, an emulator named Impact was released. It emulated Capcom's arcade systems ZN-1 and ZN-2, both based on Playstation hardware, and used the same plugin standard as PSEmu Pro. Rumors started spreading about this emulator being made by the same people who made PSEmu Pro, but at this time nobody confirmed or denied them.
On December 19, 2001, the emulator of a related machine was released: S11Emu, which emulated Namco's System 11 (another Playstation-based arcade system).
On March 23, 2002, the first version of ZiNc was released: this was an arcade emulator combining the features of both Impact and S11Emu. At the same time, the warning not to talk about Impact or S11Emu appeared on the page leading to the official ZiNc forum. ZiNc received several updates up to January 25, 2005, when version 1.1 was released. On February 18, 2006, the official site revealed that ZiNc, S11Emu, Impact and PSEmu Pro were one and the same, and the authors of ZiNc (up to version 0.9), S11Emu and Impact were indeed Duddie and Tratax. The same update promised a release of Zinc v1.2 and the Zinc source code, but nothing has been released.
R. Belmont (of MAME fame) gave a ZiNc 1.2 update in May 2007, [http://www.bannister.org/forums/ubbthreads.php?ubbshowflat&Number29522#Post29522 stating] that he was "back-burnering it until we see if smf's bluffing or not with G-NET - then 1.2 could contain every PSX-based system known to man."