This is a 16-step sequencer. It lets you create a rhythm track using the sounds of the Roland TR-909/TR-808/TR-707/TR-606 rhythm machines or samples from the selected VirtualDJ Sampler Bank, or perform rhythms by striking the performance pads.
- VALUE. Changes the value of settings such as tempo, pattern scale, or shuffle.
- SCALE Selects one of the following choices as the time value of one step.
8th note triplet : Three steps will be one beat.
16th note triplet : Six steps will be one beat.
16th note : Four steps will be one beat.
32nd note : Eight steps will be one beat.
Hold SHIFT andt hen press the button to specify the last step.
- SHUFFLE Adjusts shuffle (rhythmic swing).
- SYNC Synchronizes the tempo of the TR rhythm to the tempo of the VirtualDJ Master Deck
Hold SHIFT and use this button to enable/disable Midi Clock synchronization. When enabled, the TR sequence will start/stop playing following the playing status of the Master Deck of VirtualDJ.
- TRIM Adjusts the volume of the instrument selected by the [BD] / [SD] / [CH] / [OH] buttons.
- ATTACK Adjusts the strength of the attack if the [BD] button is selected, or adjusts the sound of the snare rattle if the [SD] button is selected. * If the [CH] or [OH] button is selected, this knob does nothing.
- TUNE Adjusts the tuning (pitch) of the instrument selected by the [BD]/[SD]/[CH]/[OH] buttons.
- DECAY Adjusts the decay of the instrument selected by the [BD]/[SD]/[CH]/[OH] buttons.
- TR-REC Lets you step-record a pattern.
Hold SHIFT down and then use this button to realtime-record a pattern using the performance pads (INST REC).
- PATTERN Lets you select rhythm patterns 1–16.
- FX ,  Use these buttons to select which of the FX1, FX2 effect units will be used to apply a VirtualDJ effect to the TR Sampler.
When FX  is selected, use the Effect unit on the left side of the DJ-808 to apply a VirtualDJ effect to the TR Sampler.
When FX  is selected, use the Effect unit on the right side of the DJ-808 to apply a VirtualDJ effect to the TR Sampler.
At the time this manual is written, the effects applied to the Sampler (both TR and VirtualDJ) are not offered in the default GUI of VirtualDJ. Hold FX1/FX2 buttons down for more than 2 seconds to load a special Sampler FX Pad page in the PADS section of the left/right deck.
Use either the Pads on the DJ-808 to control the assigned actions of the Pad page or the left/right FX unit's controls.
- START/STOP : Plays/stops the pattern.
[SHIFT] +[START/STOP] : Replays the currently-playing pattern from the beginning.
- [BD], [SD], [CH], [OH] Select the instruments when using TR-REC.
[[SHIFT] + [BD] : Assigns the instruments of the TR-909.
[SHIFT] + [SD] : Assigns the instruments of the TR-808.
[SHIFT] + [CH] : Assigns the instruments of the TR-707.
[SHIFT] + [OH] : Assigns the instruments of the TR-606.
- – Assigns a VirtualDJ sample (1 to 8) of the selected Sampler Bank as instrument.
[SHIFT] + – Selects a Sampler Bank (1 to 4) of VirtualDJ
- ACC Adds an accent to the step when using TR-REC.
- CLEAR Deletes the content recorded by TR-REC for a specific instrument, or deletes the pattern.
- TR-S pads – Use these buttons to turn steps on/off or to select patterns.
- TR FADERS Adjust the output level of the instruments (bass drum, snare drum, closed hi-hat, open hi-hat).
Note : Most of the following information have been copied from the official Roland DJ-808 Manual
Read further details about the TR Sampler in the Roland DJ-808 manual Microphone