[ams6110]

In the NeXT days, a program could be compiled as a "fat" binary that would run on multiple supported CPU architectures.

It made things easier for developers because they only had to ship one set of installation media regardless of the CPU the user had.

[Turing_Machine]

This capability still exists, and is in fact often used for libraries. The lipo command-line tool lets you bundle code compiled for multiple architectures into the same physical file (or extract the code for a specific architecture, etc.).

[detaro]

Didn't Apple have the same thing during the PowerPC->Intel migration? "universal binary" or something like that.

[marssaxman]

Apple's 68K->PowerPC transition did roughly the same thing.