So...the first thing to do is prepend the filename with "/c/" such as "/c/filename.bas". The effective root directory is "/c/", but you still need to specify it.
If you enter the command "name", it will display the current filename and it's the command you can use to change the file name (ex NAME "/c/test.bas") and then simply use the command "save" to save to that filename.
The next thing is that I would recommend you upgrade to a newer version of the operating system. I'm running 1.2.28 with no problems and I have 4 systems in long term production.
There's really a need for something like a "User's Manual" to complement the existing documentation. Paul and Iain have been extremely responsive to my inquiries, but there's a lot that's not intuitive, at least to a dummy like me!