A Java virtual machine written in Java
jjvm is a Java VM written in, and targeting, Java 1.1. The project files are from Visual J#, so you'll need some other tools to open and compile the project. Its implemented straight from the Java VM spec, which is included in the repository.
jjvm was written as part of a command interpreter for a hierarchical relational database project. It was similiar to a graph database, except that the focus was on querying and integrating distributed endpoint such as Java servlets, mainframe RPC, and web services.