Jeskola Buzz machine
A Jeskola Buzz machine is a user-created modular plug-in for the Jeskola Buzz audio software. This software is freeware but not open source; its development was paused from 2000 to 2008 because the developer lost the source code to it. It began as a tracker in the late 1990s but evolved beyond this.
End-users can add functionality to it via "machines", which can be programmed in whatever languages or frameworks can produce Windows Dynamic-link library (DLL) files, which are how Jeskola Buzz accesses them; they must be placed in particular subdirectories where the software expects to find them.