Making Music with the MSSIAH MIDI Sequencer (Commodore 64)

The MSSIAH is a MIDI cartridge for the Commodore 64.
It contains a suite of music applications that starts instantly as you insert the cartridge and start up the computer.
With these applications you can play the C64's audio circuit (SID) via MIDI or stand-alone with the internal sequencers.
more info:
http://www.8bitventures.com/mssiah/main.php