PPG (Palm Products Germany, Wolfgang Palm) Synthesizer, Germany
PPG in Synth Database 
Latest Product/Work of Wolfgang Palm: Steinberg Plex, which is something like a Workstation or Instant Synthesizer
PPG Wave disk format
there is a Linux driver to read the OS9 data format, or at least a raw driver that can be customized or so.With Windows, you will probably don't have a chance...related to the OS/9 that runs on the old Radio Shack Color Computers, which have 6809E's in them. It was a Unix-like OS that could multitask even on that little 2 MhZ (as I remember) machine. It would be cool if you could read the PPG disks using one of those . . . As far as I know, it was OS 9 (not to confuse with MacOS 9 ;-)) which was developed by some German programmers. There was a computer based on this OS and the Waveterm B used the same main board.Check with the experts: http://www.nashville.net/~antarct/ppg.htm
the PPG is the predecessor of the Waldorf Microwave 1,2,XT,XTk and Wave..