ARCHIVED: In Mac OS, what does it mean when an application is described as being 68k, PPC, or Fat?

This content has been archived, and is no longer maintained by Indiana University. Information here may no longer be accurate, and links may no longer be available or reliable.

In Mac OS, the terms 68k, PPC, and Fat indicate whether an application was written for the older 680x0 series Macintoshes, the PowerPC-based systems, or for both.

68k applications are written for the 680x0 Macintoshes (i.e., everything from the original "Compact" Macs up through the Quadra and Centris models). It should be noted that some of these programs won't run on certain models for various compatibility reasons. PowerPC systems will run 68k programs, but they will suffer in performance, because they must run the program code in an emulation mode.

PPC indicates that the program is written specifically for systems with PowerPC processors. PPC applications typically run faster than their 68k equivalents. PPC programs will not run on the 680x0 Macintoshes.

Fat indicates that the program is written with both 68k and PPC codes. The application will work on 680x0 computers as well as PPC systems. The main disadvantage is that Fat applications are larger and take up more disk space on your hard drive.