Boss DD-8 Reference Manual page 12

Using the Tempo Delay
Setting the Tempo Using a Footswitch
Connecting a footswitch (FS-5U, FS-6, FS-7; sold separately) to the
TEMPO/EXP jack lets you set the tempo delay by inputting the
tempo.
* You can input the tempo with the footswitch regardless of
whether the effect is on or off.
1. Connect the Footswitch to the TEMPO/EXP jack.
* When connecting a footswitch, you must turn off the power
before connecting or disconnecting cables. Failure to observe
this precaution will cause malfunctions.
2. Select the mode.
Use the [MODE] knob to select the mode to be used.
* Inputting the tempo is not possible in LOOP mode.
3. Start inputting the tempo.
Press the footswitch at quarter-note intervals in synchronization
with the tempo of the song. (If the effect is off, the CHECK
indicator blinks red; if the effect is on, the CHECK indicator
blinks red/green.)
Footswitch
If one FS-5U unit is
connected
12
Operation
Use the pedal to input the tempo.
Footswitch Operation
If two FS-5U units
Use the TIP pedal to input the tempo.
are connected
If an FS-6 or FS-7
Use switch B to input the tempo.
are connected
The delay time is set according to the tempo and the TAP
DIVISION value.
For example if TAP DIVISION is set to a dotted eighth note
(WARM), and you press the pedal switch at quarter-note
intervals in synchronization with the tempo of the song,
the tempo is calculated based on that spacing, and the
delay is applied with a length of a dotted eighth note at
the calculated tempo.
* Tempo input using the Pedal Switch is not possible.
* Turning the [TIME] knob resets the delay time to that
indicated by the knob's position.
* The CHECK indicator flashes red in time with the interval with
which you press the pedal.