This article outlines which computers can use the programmable function key feature of Mac OS 9.

Programmable keyboard function keys only works on computers that have the ROM-in-RAM feature (iMacs, iBooks, PowerBook G3 Series (Bronze Keyboard), Power Macintosh G3 (Blue and White), Power Macintosh G4 (all models) and later computers). Other computers do not have this button in their Keyboard control panel.