Every cell has an effect: a
number from 0 to F in the low half of its third byte, and an 8-bit parameter in its
fourth, written as three hexadecimal digits such as C20. StarTrekker’s own
list of effects is not documented in the sources used for these pages. OpenMPT reads
0 to D with ProTracker’s meanings, E as StarTrekker’s synth commands, and
F as the speed only; the explorer follows it, as below.
Ticks
Each row lasts a number of ticks, the speed, 6 unless the song sets another. Tick 0 is when the row’s notes are played. Some effects act once, on tick 0; the others act on every tick after it. A tick lasts 20 ms. x and y below are the parameter’s two hexadecimal digits, xx the whole byte.
The effects
| Effect | Name | What it does |
|---|---|---|
0xy | arpeggio | On every tick, cycles between the note, the note + x semitones and the note + y semitones. 000 is no effect. |
1xx | slide up | On ticks 1 onwards, takes xx from the period; not below 113. |
2xx | slide down | On ticks 1 onwards, adds xx to the period; not above 856. |
3xx | tone portamento | Slides towards the row’s note by xx a tick, without restarting the sample. 300 keeps the last speed. |
4xy | vibrato | Wobbles the pitch: x is the speed, y the depth. |
5xy | tone portamento and volume slide | Goes on with the last 3xx, and slides the volume as Axy. |
6xy | vibrato and volume slide | Goes on with the last 4xy, and slides the volume as Axy. |
7xy | tremolo | Like vibrato, on the volume. |
8xx | (not used) | Ignored. |
9xx | sample offset | Starts the sample xx × 256 bytes in. |
Axy | volume slide | On ticks 1 onwards, raises the volume by x, or if x is 0 lowers it by y; kept within 0 to 64. |
Bxx | position jump | After this row, goes on at position xx of the order table. |
Cxx | set volume | Sets the volume to xx, 0 to 64. |
Dxy | pattern break | After this row, goes on at the next position, at row x × 10 + y. |
Exy | StarTrekker’s synth commands | Start StarTrekker’s own synthesised sounds and macros, not ProTracker’s extended effects. They are left out. |
Fxx | set speed | 01 to 1F: the speed, in ticks a row. Above 1F is taken as speed 31, not as a tempo. F00 stops the song. |
The E commands
From version 1.2, StarTrekker could play AM and FM synthesised sounds and macros, and
its E commands start them. OpenMPT’s loader drops them, noting that it has “no assembly
macro support”, and the explorer does the same: an Exy in an FLT8 module
is played as no effect. A song that relies on the synthesised sounds plays without
them.
Speed
ProTracker reads F20 and above as a tempo. OpenMPT does not do so for
StarTrekker’s modules: it takes any value above 31 as speed 31. The explorer does the
same, so ticks stay at the starting rate of 50 a second throughout the song.