A computer that is booted into a 64-bit kernel can still run 32-bit applications. However, it cannot load 32-bit loadable kernel extension (kexts on Mac OS X). A driver that interacts with hardware requires a kext and older versions of NI Mac OS X drivers use 32-bit kexts.
Some computers that shipped with Mac OS X Snow Leopard (10.6) and all computers running Mac OS X Lion (10.7) or Mac OS X Mountain Lion (10.8) boot into a 64-bit kernel by default. If you wish to install the drivers older than the versions listed above on a computer that boots a 64-bit kernel by default, you will need to boot the system into 32-bit kernel mode. This can be accomplished by holding down 2 and 3 during boot on computers running Mac OS X 10.6 or Mac OS X 10.7. The 32-bit kernel is not available with Mac OS X 10.8.
Rosetta is no longer supported in Mac OS X 10.7 or later. Because previous versions of NI-488.2 use Rosetta, some components will not work even if booted into 32-bit kernel mode.