From Keen On Keys.

The HB 404 is the smallest model of the Master series from 1984 and the successor of the Minstrel Alfa. It has 40 mid-sized keys, 8 note polyphony, 6 sounds with sustain and single finger orchestra, 6 hythms, arpeggio and 2 chord modes.

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0:00 Intro
2:29 History
13:57 A Look Inside
18:11 Sounds
23:57 Rhythms
31:31 Conclusion
32:02 Successors
35:16 Final Performance

Listen to some tracks on Soundcloud:
https://soundcloud.com/user-229361059