Casio GZ500, GM = (General Midi) Keyboard/Synthesizer, 1998 (In Cream) And *TESTED* and Very Rare! | Reverb
Casio CTK 496 Electronic Digital Keyboard Piano MIDI MIC w/ Power Cord & Stand | eBay
Casio CTK-496 Keyboard | zZounds
Adding MIDI To An Old Casio Keyboard | Hackaday
Amazon.com: Casio CT-X700 61-Key Portable Keyboard and M-Audio SP-2 - Universal Sustain Pedal with Piano Style Action For MIDI Keyboards, Digital Pianos & More : Musical Instruments