Nintendulator is an open source Win32 NES emulator written in C++. The original goal was to emulate the NES down to its hardware quirks; though it's fallen behind over the years, recent builds have caught up once again and can emulate certain behaviors most other emulators neglect to handle. However, this emulation precision comes at a price - a 1500MHz (estimated) or faster CPU is required to emulate at full speed.
Supported file formats include .NES, UNIF, FDS (fwNES format), and NSF. Mappers are handled using external DLLs, complete with extra sound channels for most games which provide them. Other notable features include writing to FDS images (by storing the differences in separate files), Game Genie support (limited to 3 codes), customizeable controllers (including 4 player), input movie recording and playback (with re-recording), AVI capturing, and a debugger with moderate breakpoint support. Additionally, savestates and battery-backed RAM are saved within the current user's Application Data folder rather than in the application's own directory, allowing Nintendulator to function properly when not run as an administrator.