Webtendo

FCE Ultra is an open-source, portable NES/Famicom emulator based on Bero’s FCE source code. It has excellent sound emulation and support for a wide variety of in-cart expansion hardware(“mappers”). PPU/CPU timing is good(in comparison to *most* other NES emulators, which are rated poor in this area). Several VS Unisystem games are supported well. Interesting features include emulation of the Zapper and VS Unisystem light gun via the mouse, and “authentic” Game Genie emulation.

The Famicom Disk System is also emulated. An NSF player is built in. Currently supported file formats include: iNES NES/Famicom ROM images, fwNES and headerless FDS disk images, and NSF files.

Extra features include save states and screenshot saving. TCP/IP network play is supported, with a few caveats. FCE Ultra is not the fastest NES emulator available, but it is reasonably fast and it should be fast enough for most people. A CPU equal to or faster than the speed of a Pentium 200 Mhz CPU is sufficient. Oh, and it can handle Castlevania III perfectly.

The 0.98.13-pre builds and source are incomplete, and might therefore be unstable. Use them at your own risk.

FCEUXD by BBitmaster and Parasyte has a Trace Logger, a built-in Hex Editor, a Name Table Viewer, Code/Data Logger, Inline Assembler, and Game Genie Decoder/Encoder in addition to the Debugger and PPU Viewer from FCEUD.

FCEUXD SP adds conditional breakpoints and symbolic debugging.