As far as I know Berkhan Software has been asked some time ago and they allowed to copy the old Atari Omikron.Basic, also they would publish the source code if they will ever find it somewhere which will never happen I am afraid. So here you get the Omikron.Basic 3.6: OMBAS360.zip (422 K)
To get the source code into the old version of Omikron.Basic just use the new one, mark all lines and save them to a block as an ASCII file. When it asks for the name do not use .asc but .bas instead. Now you can load the .bas file in the old version via the LOAD BLOCK menu.