Tha O.S. that I need is actually for a Kohler KD165. Those files are OSPa.LZX, BPa.Sys, NBPa.SYS. The Kohler KD165 is a Digital Baby Grand piano, which is essentally the Korg PA 80, but it has 88 keys. If anyone can help me acquire this, I would be ever so grsteful!
The PA50 and the Microarranger are the same, from what I believe, so look on the Korg site