SDI is a music tracker system for the Commodore 64 and is written by Geir Tjelta and Glenn Rune Gallefoss. The system has the following features: Sequencer, tracker and a sound editor. Load, save and dump menu. DOS commands. Vibrato, pulse, filter, arpeggio and tempo. Changes in this version: Improvements for the filtercutoff routine and the play routine had a problem with the gatetimeout setting.