'[l[http://nesdev.parodius.com/nt2/[NerdTracker II] was originally a DOS-only tracker for the 2A03 (8-bit Nintendo CPU). Much of the old-school original NSFs where programmed on this. NT2 is a piece of history. Fortunately, thefox has recently programmed '[l[http://thefox.aspekt.fi/nt2-sdl-1.0.zip[NT2 for Win32] -- rejoice! Make sure you download the "ASM Replay Code" from the official homepage of NT2 to compile .NED (NT2 files) to NSF.
