I started a little A4 interface that works on top of A5. So far it can run an unmodified exstars reasonably well. All new bitmaps are memory but I'm planning on trying some hacks where the interface can figure out what bitmaps are just drawn to the screen and make those video bitmaps.

Hopefully this can become an addon to A5 but it will require a lot of hacks to get things to work so it won't work in general.

Attached is the .tar.gz with a Makefile (that just calls scons) and will build a working exstars. Right now it will try to compile with 5.1 but just hack the SConscript to use 5.0.