as the pull request seems to have gone dead I refactored his changes into a new device derived from the 7759 rather than adding the Fifo into the 7759 (due to Aaron saying it doesn't exist there)
it's possible the custom chip that Pico uses has said logic built in somehow as it's not a plain 7759 afaik.
make TARGET=mess -j19
will generate all needed files and build MESS, while developing you can use
make TARGET=mess COMPILE=1 -j19
to prevent rebuilding of make files.
Build system have automatic generate of dependencies so will do incremental builds fine.
make clean
will remove all generated files/projects and obj files
