A Scream Tracker 3 instrument can describe a recorded sample or settings for an AdLib FM sound. The difference is substantial: one plays stored waveform data, while the other asks a synthesiser chip to generate a sound. The S3M format makes room for both within a tracker song.
Sami Tammilehto, known as Psi in Future Crew, wrote Scream Tracker. Its versions need to be kept apart. PC Review’s August 1992 review describes an earlier four-channel program and an audio board connected to the printer port; it does not describe the later ST3 feature set.
The pattern is a set of events
S3M separates the song’s order list, instruments and patterns. Each pattern row can contain note, instrument, volume and effect information. An order list can repeat a pattern or move to another one without duplicating all its notes.
The original TECH.DOC assigns digital channels to left and right sample playback and reserves other channel types for AdLib sounds. It also describes distinct instrument headers: a sampled instrument needs a location, length, loop and tuning information; an FM instrument needs synthesis parameters. (Tammilehto, TECH.DOC, channel and instrument sections.)
This is why an S3M player needs more than a generic sample mixer if the song uses FM instruments. The two kinds of sound have different machinery behind the same pattern entry.
Small differences in the player matter
The format records tracker-version information and compatibility flags. One flag concerns whether a volume slide also acts on the first tick of a row. A small timing difference can change a sustained phrase even when its note names are unchanged.
Later Impulse Tracker deliberately followed Scream Tracker’s working style. Jeffrey Lim’s manual praises the way music could be entered and explains his decision to build on that interface. That is an author’s explanation of his design, rather than a measure of which tracker every musician preferred.
The family connects DOS sound hardware with the module tradition: reusable musical data, instruments and a player that must understand their particular rules.
Sources
- Sami Tammilehto, Scream Tracker 3.20 File Formats and Mixing Info, TECH.DOC: original official technical document, preserved in a parser project.
- PC Review, August 1992: contemporary review of the earlier Scream Tracker edition.
- Jeffrey Lim, Impulse Tracker User’s Manual, sections 1.2 and 2.7: participant explanation of Scream Tracker’s influence.