What?!?

Unless I am missing something in your post, Bebop, I have to tell you that is certainly is possible to do what you are talking about. I can play a MIDI file that is on my computer in my Tyros that is connected by USB cable. I can play it using Windows Media Player, WinAmp or MidiPlayer. But, I have to go into Control Panel, Sound and Audio Devices, and make sure I have selected the Yamaha USB for MIDI out.

Even a lower model PSR can do this. As long as you have a MIDI interface in place. Something like the M-Audio 1x1 or the Midisport Uno. You must still configure your computer to use the Yamaha keyboard as the MIDI device.

I don't know what Steve was thinking. Perhaps you haven't explained the situation completely?

Tom G.