My ultimate aim is to include re-assemblable sources for the official GCE roms here.

I'll be adding them slowly and the files are unlikely to be fully reassemblable at
first - they'll get better with time and I would appreciate any improvements that
anyone might make.  Contact me by email at gtoal@gtoal.com with updates.

To be fully reassemblable, you need to be able to insert a NOP near the start
of the code and still have everything work correctly.  It would be nice to also
be able to add an extra byte of data before the data that was used and still have
it work. But that may be harder to arrange.