Pre 0.70 Pattern Effects

Pattern effects are used to modulate sounds in various ways and can be used in both patterns as well as (if/once supported) tables.

Effects between the sound sources (PSG, FM, and PCM) are all distinct. That is PSG effect 1234 could be different for FM and PCM.


Implemented Effects

Hex Effect Persistent
00xx Pitch Slide Down No
01xx Pitch Slide Up No
02xx Pitch Sweep Down Yes
03xx Pitch Sweep Up Yes
04xx Volume Slide/Sweep Down/Up No/Yes
05xx PWM Slide/Sweep Down/Up No/Yes
06xx PWM Set Value No
07xy Arpeggio Yes
08xx Glissando (Glide) Yes
09xy Vibrato Yes
0Axy Tremolo Yes
0Bxy Pulsolo Yes
0C.. Stop Song Global
0D.. Pattern Break Global
0Exx Set Song Speed Global
0Fxx Jump to Order Global
10.. Reset Channel No
11.. Global Transpose Global
12xx Pitch Speed Multiplier No

Glissando (Glide)

Glissando, also known as Glide and in the Eurorack world as slew, will slide to the target note at a speed of xx. This effect is persistent meaning once enabled, it will continue to slide to the last note played in the pattern. This includes if swapping instruments in the same channel.

To disable, set the speed to 00

Vibrato, Tremolo, Pulsolo

These effects work a tad differently than some trackers. Instead of speed and depth, DreamTracker uses loop-length and depth. Subtle but important difference where loop-length (the first number) sets how big the triangle loop is.

The triangle loop is made by adding a the depth constant to the base channel pitch/vol/PWM for half the loop and then subtracting it for the rest of the loop. When playing a new note, the loop position is reset to 1/4th of the loop (halfway through the up stage) which is close to the zero cross.

This means x and y are perhaps more coupled than they are in other trackers.

If all that didn’t make any sense, don’t worry, it works mostly the same as other vibratos. x is, more or less, speed and y is more or less the depth.

To disable set depth (y, or the 2nd parameter) to 0.

Slides vs Sweeps

Slides are single shot. That is to say, they run once when you put specify the effect for a channel. If you want the effect to fire multiple times, you have to specify it. This is by design because it allows for intentional coarse stair-step style sounds as well as slicer/stacatto, among other things.

Sweeps, however, are continual and run until they are turne off by specifying 00 (for example 0500). They also run at the same speed as the sound engine which means they are much smoother and faster. They can be thought of like a simple linear envelope in this way. If you want to make a kick-drum from a square-wave, you’ll want to use a sweep.

Some effects combine slide/sweet and direction in one command. This is because the VERA only supports volume and PWM from 00-3F. We can use the top bits to add more function. If that sounds complicated, don’t worry, just use the table below:

Range Function
00-3F Slide Down
40-7F Slide Up
80-BF Sweep Down
C0-FF Sweep Up

Global Transpose

Changes the global transpose value to the one provided. It is signed meaning putting in 11FF would transpose down by 1 semitone, 11FE by 2, etc. Putting in 1101 would transpose up by 1, 1102 up by 2, etc.

Pitch Speed Multiplier

This sets the channel pitch shift value, which controls the speed that pitch sweeps and glides run at. This value corresponds to how many bit shifts to shift the glide or sweep value before adding it to the note.semitone values. The default value can be set for each instrument (see Vera Instruments).

Volume Column Effects

Since the volume range of the VERA is 00-3F, the upper values can be used for other things, such as panning, changing the wave or setting the PWM.

Range Function
00-3F Volume
40-7F Channel Attenuation
80-BF Set PWM
C0 Pan Center
C1 Pan Left
C2 Pan Right
C3 Set Wave to Pulse
C4 Set Wave to Saw
C5 Set Wave to Tri
C6 Set Wave to Noise
TBD Turn off vol env
TBD Turn on vol env
TBD Turn off pwm env
TBD Turn on pwm env
TBD Turn off pitch env
TBD Turn on pitch env
E0 Legato Off (TBD)
E1 Legato On (TBD)

Channel Attenuation

The range 40-7F is used to set attenuation. This value is subtracted from the channel volume before it is written out to the VERA. This can be extremely useful if wanting to, for example, use multiple channels to simulate delay. The attenuation is always applied to the volume and is global to the channel.


Here are currently implemented and planned effects. There will likely be more than is listed currently, but these are either what works today or what will be available soon.


Hex Effect Persistent
00xx Pitch Slide Down No
01xx Pitch Slide Up No
02xx Pitch Sweep Down Yes
03xx Pitch Sweep Up Yes
04xx Volume Slide Down/Up TBD
05xx Volume Sweep Down/Up TBD
06-x Legato TBD
07xy Arpeggio TBD
08xx Glissando (Glide) Yes
09xx LFO Waveform Global
0Axx LFO Frequency Global
0Bxx LFO AM/PM Depth Global
0Cxx Mod Sense. (Vibrato/Tremolo) TBD
0Dxx Channel Attenuation TBD
0Exx Ch. 7 ($17) Noise Control Yes
0Fxx (TO ADD: Global to Op Vol) Yes
10.. Reset Channel No

FM Channel Register Effects

These directly control the channel registers.

Hex Effect Persistent
40xx M1 Fine Detune and Frequency Mult Yes
41xx M2 Fine Detune and Frequency Mult Yes
42xx C1 Fine Detune and Frequency Mult Yes
43xx C2 Fine Detune and Frequency Mult Yes
44xx M1 Volume Yes
45xx M2 Volume Yes
46xx C1 Volume Yes
47xx C2 Volume Yes
48xx M1 Key Scale and Attack Yes
49xx M2 Key Scale and Attack Yes
4Axx C1 Key Scale and Attack Yes
4Bxx C2 Key Scale and Attack Yes
4Cxx M1 AM Enable and Decay 1 Rate Yes
4Dxx M2 AM Enable and Decay 1 Rate Yes
4Exx C1 AM Enable and Decay 1 Rate Yes
4Fxx C2 AM Enable and Decay 1 Rate Yes
50xx M1 Coarse Detune and Decay 2 Rate Yes
51xx M2 Coarse Detune and Decay 2 Rate Yes
52xx C1 Coarse Detune and Decay 2 Rate Yes
53xx C2 Coarse Detune and Decay 2 Rate Yes
54xx M1 Sustain and Release Yes
55xx M2 Sustain and Release Yes
56xx C1 Sustain and Release Yes
57xx C2 Sustain and Release Yes
58xx Pan, Feedback and Algorithm Yes
59xx PM and AM Modulation Sensitivity Yes

Noise Control

Enables/Disables the noise waveform on modulator C2 of channel 7 and controls the noise frequency. The lower 5 bits control the frequency. Values $80-$9F enable the effect and set the frequency.

Volume Column Effects

Since the volume range of the YM2151 is 00-7F, the upper values can be used for other things, such as panning, etc.

Range Function Persistent
00-7F Volume (TBD) Yes
C0 Pan Center Yes
C1 Pan Left Yes
C2 Pan Right Yes
E0 Legato No


Normally when playing a note, a note release is sent to the YM2151 immediately followed by a note-on. This resets the enveloeps and things. Sometimes it may be desirable to let the envelopes run while changing the note played, and this is what legato does. Guitar players can think of it as “pull-offs” in a way.

It is evaluated only for the current note being played. I may add a toggleable version (e.g. perhaps E1) which could be used when needed.


PCM has no effect support yet beyond volume, but a few effects are planned:

Since we have a lot of room in the volume column, there may be combinations, such as using the Volume to fine two sample offset.