http://developer.x-plane.com/2012/11/64-bit-is-here/
X-Plane 10.20 is the first 64-bit version of X-Plane 10. It comes with two sets of executable applications for X-Plane:
Macintosh: X-Plane.app (64-bit) and X-Plane-32bit.app (32-bit)
Windows: X-Plane.exe (64-bit) and X-Plane-32bit.exe (32-bit)
Linux: X-Plane-x86_64 (64-bit) and X-Plane-i386 (32-bit)
Linux users: note that the canonical app names have changed to match the standard ABI suffices for Linux; if you launch x-plane with a script, you can either mod the script or sim-link from the old app name (X-Plane-i686) to the app you wish to run.
X-Plane 10.20 does not contain 64-bit versions of Airfoil Maker or Plane-Maker; we do not have any plan to 64-bit-ize them at this time.
Be sure to read the X-Plane 64-bit FAQ!
Known Issues:
The 747 plugin is not 64-bit safe yet, so some 747 nav systems will not operate in 64-bit mode.
The current installer is not updated for the new file naming convention and will always launch the 64-bit app (Windows/Mac), or fail to relaunch the app (Linux). You can simply restart X-Plane from your desktop after updates.
There are a number of open bugs that we are looking at that will be addressed in later betas.
Na denn viel Spaß.
Gruß
Dieter