Erik Silverson inquired about compatibility in Digest 960313.

As I understand matters, the older Yamaha Disklavier pianos will 
accept only their "native" disk file format, known as "ESEQ".  Later 
production pianos also have a limited capability to accept MIDI 
files.  PianoDisc files, to my knowledge, are standard MIDI format 
and my be reproduced on any MIDI device.

 [ Editor's Note:  I've had some dealings with PianoDisc PDS-32 and
 [ PDS-128 systems.  The PDS-32 systems, if upgraded with the latest
 [ software will play all Yamaha disks that I've tried.  I don't know
 [ for a fact that they will play "older" Yamaha disks.
 [
 [ Unfortunately, PianoDisc will not read or write DOS disks containing
 [ standard MIDI files.  Of course you can "record" a standard MIDI file
 [ onto a disk in PianoDisc format by by playing the MIDI file on a PC
 [ with a MIDI interface and recording on the PianoDisc unit via the MIDI
 [ cable.  There is at least one commercial program for doing this
 [ conversion directly as well.

The "continuous pedal data" is generated by a position transducer 
which is rather casually connected to the loud-pedal pushrod on the 
pedal-lyre of the Disklavier.  Also, this pedal-position information 
is recorded with equal casualness whenever the computer feels like 
it!  I recommend ignoring this recording mode.  Fortunately, 
ordinary "on-off" pedal data is always recorded to the disk file, 
and any solenoid piano or piano synthesizer will properly reproduce 
the pedaling.

Visit a big, old-time piano store which sells Yamahas.  It's likely 
that they can show you a new piano (perhaps a Yamaha) equipped with 
a PianoDisc system, which costs quite a bit less!  At a nice store 
like this you can verify compatibility.

-- Robbie Rhodes