SEMBERIA BASIC is an extension to the built-in BASIC of the Commodore 64 that adds 27 new commands and has the ability to be appended to your program so that the extension doesn't need to be loaded beforehand.  Additionally, the extension includes the source code so that you can modify any commands as needed. The author of the SEMBERIA extension is prof. Samir Ribić, Ph.D. from Sarajevo, Bosnia and Herzegovina.

Included in the archive is a .d64 image, a .tap image, source code and complete manual.

The original source and announcement for this program is this post on the Lemon64 Forum.