Callisto is a virtual arranger organ that uses pre-made MIDI pharses as musical styles and by that, allows one man band performance, just like other known hardware arrangers. In this concept, Solo performance are played by right hand while The left hand is used for switching chords. Callsto is actually a MIDI tool that uses other instruments to make sound. It can connect itself to any other VST instrument that opened in the DAW and send the style's MIDI pharses to it by using MIDI channels. Callisto has total 10 variations that can be swithched by dedicated knobs, just like in the hardware virtual arrangers. it has it's own tempo knob (can be synced to the DAW), "variation hold" button, "play\stop" button, instruments muting abilities and keyboard splitter. It can play in both "arranger mode" or "piano mode" and can also play right hand instruments in "single mode" or "multi mode". Callisto connects itself to VST instruments that opened in your DAW by using the DAW's internal MIDI channels mechanism. Each channel of the total 12 channels represents one instrument slot (Callisto has 12 instrument slots. 6 slots for style components and 6 for solos).