Yamaha SY99 Owner's Manual page 20

Record additional tracks 8. As desired, repeat steps 5, 6 and 7 to select and record additional tracks.
Note:
A more complete explanation of using the SY99 sequencer is given in the
following section How to use the sequencer, which explains how to set up
your own Multi, create rhythm patterns, arrange the rhythm patterns in track
16 (the pattern track), record additional tracks, edit the song, name it, and
save the finished song to disk. Refer to page 48 for details regarding the
save procedure..
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