To add more detail, both OS2.x and OS3.x require the Zorro riser board to be fitted. Without it, you'll usually end up with a yellow error screen.
However, the computer will boot correctly to the early startup menu if the 1.4 "softkick" ROMs are fitted and without the riser board fitted. If you then boot OS2.x or 3.x ROM images, it'll fail as mentioned above.
