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. The PC
trackers that wrote these files took the effects over from ProTracker, so the numbers and
their meanings are ProTracker 2.3D’s, as below. Each tracker may play them a little
differently in the details.
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. At the default tempo 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, raising the pitch. ProTracker stops at 113; the explorer lets these files go up to 57, the top of octave 4. |
2xx | slide down | On ticks 1 onwards, adds xx to the period. ProTracker stops at 856; the explorer lets these files go down to 1,712, the bottom of octave 0. |
3xx | tone portamento | Slides from the current pitch 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. 0 in either keeps the last value. |
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 | panning | Unused in ProTracker. Many PC players read it as the channel’s position between left and right. The explorer ignores it. |
9xx | sample offset | Starts the sample xx × 256 bytes in. 900 uses the last value. |
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; above 64 is taken as 64. |
Dxy | pattern break | After this row, goes on at the next position, at row x × 10 + y (decimal digits). A row above 63 means row 0. |
Exy | extended | One of the 16 extended effects, chosen by x. |
Fxx | set speed or tempo | 01 to 1F: the speed, in ticks a row. 20 to FF: the tempo, in beats a minute. F00 stops the song in ProTracker. |
Extended effects
| Effect | Name | What it does |
|---|---|---|
E0x | filter | Switches the Amiga’s low-pass filter. It has no meaning on the PC. |
E1x | fine slide up | Takes x from the period once, on tick 0. |
E2x | fine slide down | Adds x to the period once. |
E3x | glissando | x = 1: tone portamento moves in whole semitone steps; 0: smoothly. |
E4x | vibrato waveform | 0 sine, 1 ramp down, 2 square (3 is also square); add 4 to keep the waveform’s position when a new note starts. |
E5x | set finetune | Uses finetune x for this row’s note. |
E6x | pattern loop | E60 marks the start of a loop; E6x goes back to it x times. |
E7x | tremolo waveform | As E4x, for tremolo. |
E8x | (not used) | Karplus-Strong in ProTracker 1; ignored by ProTracker 2.3D and by the explorer. |
E9x | retrigger | Restarts the sample every x ticks. |
EAx | fine volume up | Raises the volume by x once. |
EBx | fine volume down | Lowers the volume by x once. |
ECx | note cut | Sets the volume to 0 on tick x. |
EDx | note delay | Plays the row’s note on tick x instead of tick 0. |
EEx | pattern delay | Holds this row for x more rows’ time. Effects go on; the notes are not played again. |
EFx | invert loop | ProTracker’s invert loop, which inverts the sample’s loop bytes one at a time as it plays, at a rate set by x. |
How the explorer plays them
There is no single reference player for these files, so the explorer uses
ProTracker 2.3D’s replay routine, with every channel the signature gives, and keeps its
behaviour in the details: a sample number without a note changes the volume at once,
9xx on a row with a note is applied twice, the tremolo ramp looks at the
vibrato position, a tempo change takes effect one tick late, and F00
stops the song.
One change is the explorer’s own, because PC trackers write notes ProTracker cannot
play: a note outside ProTracker’s three octaves keeps the period it was written with,
moved by the finetune; slides run from 57 to 1,712; and an arpeggio on such a note
works by the ratio between semitones. Inside the three octaves, notes are played from
ProTracker’s tables. The tracker a file was made with may still play it a little
differently, and 8xx panning is not followed.