Roland DR-880 Owner's Manual page 129

5. When you've made the setting, press
[EXIT].
The message "Now writing..." will appear,
and the currently setting will be saved.
When the currently setting have been saved,
the message will disappear.
* Do not turn off the power while the message is displayed.
Your data may be damaged if you do so.
Tempo when operating as a slave
When the DR-880 is operating as a slave, you
can't control the tempo from the DR-880 itself.
Synchronizing the DR-880 with a digital recorder or MIDI sequencer
129