Windows: ; thanks to JAC! from AtariAge
Go to the CMD shell and there to the directory, where the 2 files are, which should be combined, then type:
copy /b file1.rom+file2.rom allinone16k.rom
and the resulting rom file can be found in the same directory. Done. :-)
Mac:
Start application Terminal and then type cd and a blank. Drag the folder, in which the 2 files are, directly behind the blank. Check with typing ls -a, whether the 2 files can be seen. Then type:
cat file1.rom file2.rom > allinone16k.rom
and the resulting rom file can be found in the same directory. Done. :-)