From GameBrew - a wiki dedicated to Video Game Homebrew.
SIDPlayer is a replayer program for C64 music (SID tunes), like PlaySID on the Amiga or SIDPLAY for Unix. You can think of it as being a stripped-down C64 emulator that only emulates the CPU and the sound chip of the C64. SIDPlayer can replay SID tunes in the PSID file format, but it cannot run any C64 programs.
This is a port of SIDPlayer, by Christian Bauer, with modifications for the NDS by Troy Davis (GPF).
It was participated in the Neoflash Summer Coding Competition 2006 (winner).
19 demonstration SID tunes are included with SIDPlayer in the sid directory.
Supported file formats
The only SID tune file format supported by SIDPlayer is single-file PSID files (these have the signature PSID in the first 4 bytes).
Most SID music available on the Internet is in this format, directory browser requires they have the extension .sid or .SID.