<P> The Alt key should not be confused with the Altmode key (sometimes also labelled Alt) on some Teletype and ASCII terminals, which is a synonym for the ASCII escape character . </P> <P> The Alt key has come to replace the Meta key of the old MIT keyboards . In their original function, both Alt and Meta would set the high bit of the signal generated by the key to 1 (for example, A generates 01000001 while Alt + A generates 11000001). However, in modern software, due to the requirement of the high bit for internationalization, Alt no longer works in such a way . </P> <P> Since the 1990s Alt has been printed on the Option key on most Mac keyboards . Alt is used in non-Mac software, such as non-macOS Unix and Windows programs, but in macOS it is always referred as the Option key . The Option key's behaviour in macOS differs slightly from that of the Windows Alt key (it is used as a modifier rather than to access pull - down menus, for example). </P> <P> The Alt key is well known as part of the key combinations: </P>

How to do alt codes on a mac