From Keen On Keys.

The DJ-1 is a small keyboard with 32 mini keys, 25 tones, 30 patterns, 6 pads, scratch and pitch disk, microphone, voice effector and a cassette recorder. Released in 1992, it was the successor of the famous Rapman. It was also released as Rap-2 or "Rap Studio".

Support this channel and buy a song or album on Bandcamp:
https://keenonkeys.bandcamp.com

0:00 Intro
0:23 Overview
1:54 Rap Studio
4:25 Other Models
5:36 A Look Inside
11:15 Tones
13:27 Pads + Disks
15:04 Patterns
16:11 Voice Effector
20:26 Cassette Recorder
24:38 Tape Speed
26:01 Feedback Recording
28:26 Channel Selector
31:50 Adding FX
36:14 Multitrack Recording
39:02 Conclusion
39:54 Outro

Listen to some tracks on Soundcloud:

Simon the Magpie’s circuit bending video:
https://www.youtube.com/watch?v=qIPKGCH818g