via this auction
"This nice Realistic C-200 Keyboard is actually a Casio VL-Tone 1 clone specifically built for Radio Shack stores!
The Concertmate-200 is a monophonic VL-Tone 1 (VL-1) synthesizer with built-in calculator. The "M+" calculator memory also stores the timbre, ADSR, vibrato and tremolo setting for the synthesizer, and the short 29 buttons mini- keyboard could be transposed by a switch to low, mid and high pitch range. (In Germany the VL-1 became very famous by the pop group Trio's song "Da Da Da", which features the "rock" rhythm and piano sound of this tiny white keyboard.) The VL-1 was the first genuine "Volks- Synthesizer" and came out even earlier than the well known Yamaha DX-7. It was first released as the Casio VL-Tone 1, and later as the Realistic Concertmate-200.
Overview
29 Button Micro-Keys
Monophonic Main Voice
5 Preset Sounds : piano, fantasy, violin, flute, guitar (selected by slide switch with a small delay)
10 Analog Rhythms : march, waltz, 4-beat, swing, rock-1, rock-2, bossa-nova, samba, rhumba, beguine
24 Preset Patterns (8 Drum Rhythms / 8 Accompaniments / 8 Funny Arrangements)
Volume Slider Control
Tempo Slider Control
3 Octave Transpose Switch
Full-Function Built-in Calculator
ADSR synthesizer (uses calculator memory as sound parameter register)
LCD (displays calculator stuff and e.g. note values)
Demo Button (plays German folk song)
Tuning Trimmer (located case bottom)
Simple Sequencer (100 Notes, Editor Insert & Delete with Battery Backed-Up)
2 "One Key Play" Buttons (play and change note duration)
Built-in Amp-Speaker System
Jacks for AC Adapter & Line/Headphone Out
Operates on Batteries or Optional (not included) AC Adapter
Special Note
The Realistic C-200 Portable Electronic Keyboard is part of the Casio VL-Tone 1 synthesis series.
The C-200 is a monophonic sound generator based on multi-pulse square-wave tones with different digital envelopes. The digital envelopes with audible zipper noise are linear, and the analog rhythms consist of 3 (high, low, snare) sounds made from square-wave and shift register noise.
The C-200 Synthesizer has a fun variety of fantastic voice tones to modify and drum rhythms to play to."
