Starting from this release, the 32-bit and 64-bit versions of PixInsight are two completely independent applications on all supported platforms. This means that PixInsight-x86 and PixInsight-x86_64 can be installed on the same machine without interfering each other. They can also be executed at the same time without problems, and each one receives and installs its own updates independently.
The configuration files for the 32-bit and 64-bit applications are obviously different now, contrarily to previous versions. The conversion from the old configuration scheme to the new one is completely automatic and transparent, and is carried out the first time PixInsight 1.6.9 is executed.
This feature is particularly useful for developers. PixInsight modules can now be developed for 32-bit and 64-bit architectures more easily from a single user account.
This separation between architectures is also very important on Mac OS X. The reason is that the only Tier-1 release of PixInsight for Mac OS X continues being the 32-bit version, while the 64-bit version, although it has been significantly improved in PI 1.6.9, still has a few GUI issues and glitches that slightly reduce its usability. You can now run both versions on the same Mac, enjoying the GUI performance and perfection of the 32-bit version while the 64-bit version allows you to process huge images making use of all available memory much more efficiently.