NESticle is one of the most popular DOS/Win95 based emulator for the Nintendo
Entertainment System written in C++/Assembly.
It is freeware and it is not to be distributed with game
ROMs and it is not to be modified or sold.
A majority of the NES technical information used to create this
came from Marat Fayzullin's (email@example.com) great NES.DOC.
Sound information was provided by AJG, Fanwen, Mikael Iushin and Y0SHi.
The major negative aspect is, it's no longer being updated or supported. The DOS version has much better emulation that the windows version.