Tracker music: a beginner’s guide to MOD, XM, S3M and IT

Long before streaming and even before MP3 was common, a generation of musicians in the demoscene, on the Amiga and on early PCs wrote music in trackers. The files they produced, known as modules, are still played and still being made, and they remain some of the smallest, most charming music files you will ever meet.

What makes a module different

An MP3 stores the recorded sound wave. A module stores the score and the instruments: a set of short digital samples plus a grid of notes (the “pattern”) saying which sample plays at what pitch and when. The player acts like a tiny synthesiser and assembles the music in real time. Because samples are reused, a full song can fit in tens of kilobytes.

Timeline of tracker software from 1987 to 1995 — Tracker software from 1987 to 1995.

The four classic formats

Extension	Origin	Notes
`.mod`	ProTracker on the Amiga	Four channels, 8-bit samples; the original sound of the scene.
`.s3m`	Scream Tracker 3 on PC	Up to 32 channels, improved effects and stereo handling.
`.xm`	FastTracker 2	Instruments with envelopes, extended pattern effects.
`.it`	Impulse Tracker	Advanced features: NNA (new note actions), filters, 64 channels.

Reading a pattern

Trackers lay out music vertically. Each column is a channel, each row a step in time. A cell might read C-4 01 40 A04: note C in octave 4, sample 01, volume 40, effect A04 (a volume slide). It looks like a spreadsheet because that is essentially what it is, and it is why tracker composers often describe their craft as closer to programming than to performance.

Why modules are still relevant

Tiny size makes them ideal for games, demos and web projects.
Open and inspectable. You can open a module and see exactly how a track was built, which makes it a superb learning resource.
Active community. New modules appear every week; the format never went away.

JahSing 3 library list after a scan, showing tagged songs, a tracker module with a MODULE label and a file with no tags — A tracker module (marked MODULE) in the same JahSing 3 library as ordinary songs.

JahSing 3 Track information window for a tracker module, listing format, channels, tempo and instruments — Track information for a module: format, channels, tempo and instruments. Sample module made for this article.

Playing modules

Modules need a player that can render them. JahSing 3 plays .mod, .xm, .s3m and .it files with pattern and sample information, a direct descendant of the module support in JahSing 2, so your collection of tracker files can live in the same library as your FLAC albums.

Where to find music

Community archives of tracker music host many thousands of modules, searchable by artist, format and year.
Demoscene party releases are usually distributed with permission to share freely.
Always check each composer’s licence or notes: “free to download” is not always “free to reuse”.

Try writing one

Modern trackers such as OpenMPT (Windows) and Schism Tracker (cross-platform) are free. Start by loading an existing module and changing a single note. Hearing the change instantly is the fastest way to understand how it all fits together.