When GFA was written the bios only had devices 0 to 5, thus it does not work correctly with bios devices 6 and up when the TT030 appeared with extra serial ports. I'm not going to go into details why it fails, suffice it to say its messy, and OUT generates strange error messages if these device numbers are used.
I've now corrected this situation so devices 6 and up are now working. Rewritten commands:
INP(), INP&(), and INP%() (byte, word, long input respectively)
OUT, OUT&, and OUT% (byte, word, long output respectively)
By some stroke of luck INP?() and OUT?() (inquire device status) happen to work fine, but I added some error checking in the runonly interpreter that should have been there.
These changes will require a new compiler and library and runonly interpreter.
OPEN does not support the extra devices. In order to fix OPEN a complete rewrite of the entire I/O sub-system in GFA would be required. Not something I really want to do. The 8 device commands above should be enough to write code for the new devices.