Impulse Tracker

Impulse Tracker is a multi-track digital sound tracker (music sequencer) which proliferated on the DOS platform. It was authored by Jeffrey "Pulse" Lim, and example music was provided by Jeffrey Lim and Chris Jarvis.

The software was distributed as freeware, though the author supplied extra features, such as support for WAV output and IPX networks, for a fee (in the order of US$30). After the stereo WAV writer plugin was publicly pirated, the original author announced that he would discontinue development after version 2.14. Impulse Tracker's interface was very similar to and could be considered the spiritual successor of ScreamTracker 3. It was comparable to its rival FastTracker. The entire program was coded in Assembly language.

Like in most module editors, music is arranged on a grid of channels. Each supports note on and note off instructions similar to MIDI. Impulse Tracker modules use the .IT file extension.

One of the features which set this MOD editor apart was NNAs, New Note Actions. If a note on command is received on the same channel as another instrument which is still playing, NNAs allow the user to customize the subsequent action:

Cut: The new instrument replaces the current instrument.
Continue: The old instrument continues to play using its ADSR curve.
Off: The old instrument begins the release section of its ADSR curve.
Fade: The old instrument fades out to 0 volume at a designated rate overriding the ADSR curve.
Another feature that set Impulse Tracker apart from other trackers was its support for hardware MIDI channels on the Gravis Ultrasound, InterWave and Sound Blaster 32 card families (provided enough RAM is available).