I have acquired an S 50 and downloaded the OS from the net but found no instructions on how to install it!

Can anyone help. I hve copied the system onto a DOS formatted disk, but it is refusing to accept this!

You have copied the system to disk with the Sdisk utility, or you used the DOS copy command?
The Roland disks must be created on floppy disks with the Sdisk utility, or they will not work!
The Sdisk program is available from Roland site http://www.rolandus.com/SUPPORT/SOFTWARE/PCSAMP.HTM

Look for aditional info on topic S330 System Disk, is this forum (last post on 11-08-99)

Mgomes