The Stereo Boombox, with built- in mini- keyboard, is one of the rarest and most mythical Casio instruments. The original German retail price of the Casio KX-101 in a German Conrad catalogue from 1986 was 1199DM (about 600€).

Main Features:
• 37 mini keys
• 12 key buttons + 11 select buttons for direct selectable single finger chords
• 2 detachable 2-way loudspeaker boxes (with some bass, tweeter is slightly hissy)
• main voice polyphony 4 notes (only 1 in unison mode)
• 9 preset sounds {piano 1..3, harpsichord, organ, clarinet, flute, horn, mellow}
• 12 preset rhythms {waltz, ballad, swing, enka, 16beat, rock-1..3, disco-1..2, bossa nova, samba}
• preset sounds, rhythms & sequencer note lengths selected through keyboard keys
• cipher buttons {'0'..'9', 'set', 'c'} (only used by tape deck?)
• main volume slider
• treble & stereo balance sliders
• separate volume sliders for poly (keyboard main voice), mono, chord, arpeggio, rhythm, mixing microphone
• stereo/ mono switch
• tempo +/- buttons (57 steps, most are slow)
• transpose +/- buttons (13 semitone steps)
• arpeggio
• detuned chorus mode (called "unison", monophonic)
• 3 rhythm fill-in buttons
• complex sequencer (473 steps, polyphonic with edit features, saves music files on audio cassette)
• 2 "one key play" buttons (to play or edit sequencer contents note by note)
• semi- analogue sound generator similar like Casio VL-1; the digital envelopes (with audible zipper noise) are linear and thus sounds unrealistic because they fade silent too soon. Unlike the latter it is 4 Note polyphonic and alternatingly assigns notes to both stereo channels. Chord voice is 4 Note polyphonic with fixed timbre like Casio PT-30 but has an optional arpeggio voice. Analogue percussion corresponds to PT-30.
• very complex multi- chip hardware:
o CPU1= "NEC D1868G 006, 8348XK, Japan" (80 pin SMD)
o CPU2= "NEC D1879G 002, 8343XK, Japan" (80 pin SMD)
o 2x SRAM= "HD C, 61914, 4F, 23" (44 pin SMD)
o tape drive CPU?= "Toshiba TC4514BP, 8418H, Japan" (24 pin DIL)
o IC "LB1405, 4A3" (16 pin DIL)
o tuner IC "441, A04" (16(?) pin DIL)
o big hybrid "K4F25S, 46311"
• radio tuner:
o FM stereo, MW, LW
o analogue scale with tuning knob
o telescope & ferrite antenna
o nice sound
• digital controlled cassette deck:
o "computer play" drive control buttons {space search, rec return, repeat, single, program, shuffle, intro, JP}
o direct title select through cipher buttons
o tape sorts switch {normal, CrO2, metal}
o tape counter (mechanical)
o record mute button (records a pause)
o datasette function to save & load sequencer data
o 2 integrated microphones
o has no dolby, sounds bassless
o fails by hardening rubber parts
• level meter (7 LED row with only 5 steps, mono)
• timer switch (to be used with an external mains timer to play or record)
• RAM-Pack slot (for optional Casio RA-10 module that expands sequencer memory to 985 steps)
• tuning trimmer (+/- 30cent)
• auto- power off (in keyboard mode)
• jacks for mains cable, speakers, line out, phones, line in, microphones, mixing microphone