What is it?

The NES Sound Format (.nsf) is used for storing and playing music from the NES and related systems. It is similar to the PSID file format for C64 music/sound, where one rips the music/sound code from an NES game and prepends a small header to the data. An NSF player puts the music code into memory at the proper place, based on the header, prepares sound hardware, then runs it to make music. An NSF can be played on NES/Famicom hardware or in an emulator (NSF player or NES emulator).

Why did you make it?

It seemed that no similar project existed, so Fisher made this one.

What makes it special?

The first publicly available hardware NSF player, it can play some NSF music below 32k and supports switching internal tracks.
Currently it supports RP2A03/Clone music chip (does not support any sound expansion chip), and uses Altera CPLD+SDRAM to make the entire NES peripheral circuit, so the hardware is very simple. It can also switch the playback speed to 50/60Hz.
It currently only supports playing some NSF format music less than 32kb, please do not try larger files. The project is still under development, and plans to support more expansion chips and larger NSF file playback in the future.