This months issue (September 2001) of "Nuts & Volts" magazine has
two MIDI articles.  The first article in the magazine describes a
MIDI-to-mechanical actuation (keyboard or hammer or valve) that
contains a built-in memory chip that can remember 4096 notes or about
683 seconds of music, whichever comes first.  The memory allows the
interface to remember music when hooked up to a MIDI source and then
play the music perfectly without the MIDI source.  The memory is not
lost when power is cut off.  Visit http://www.nutsvolts.com/

Robert Lang