The PowerRoll takes standard MIDI input to play music and will work
with a Mac with MIDI interface.  There are a two major complications
however.

First is the fact that the pedal codes of a MIDI file which is not
made specifically for the attached piano will not pass through properly
to the piano without software intervention.  To play properly, either
software specifically made for the attached piano or interpreting
software must be used.  I make such files for the Duo-Art in MIDI
format but am unaware of any such files for the Ampico.

It is possible to use WindPlay to play the BAR ANN files that are
available for the Ampico using the Mac and a Windows emulator such as
Virtual PC.  I tried this in the past with a rather slow Mac and the
results were passable.  Unfortunately WindPlay uses machine resources
extensively and is even demanding of a PC in many situations.  Newer
Macs with their faster processors may work acceptably with Virtual PC.
It may also help to turn off the piano roll display.

The next most serious problem is that fact that the PowerRoll uses
MIDI notes 0 and 1 as motor turn off and turn on signals.  If a
turn-off signal is not given to the PowerRoll and the unit is not
turned off manually, the pump will run indefinitely and possibly
overheat and cause a fire.

These old motors are not thermally protected and many have not been
maintained properly.  They are wound with cotton covered wire which may
have become saturated with motor oil.  It is therefore essential that the
files for use with PowerRoll have a motor turn off signal at the end,
or that they be played with a player that provides the signal.  This is
not going to be the case with ordinary MIDI files played on either the
Mac or the PC.

I plan to offer Ampico MIDI files in the future but do not have a
source for Ampico rolls to scan.  I have been offered rolls, but none
have been forthcoming.

Spencer Chase
http://nt.mcn.org/spencer/