64-bit CPU support

SIMION® 8.1 provides a native 64-bit executable, in addition to a 32-bit executable as before. The 64-bit executable allows much larger potential array sizes that utilize larger amounts of RAM.

The problem with 32-bit executables is that they are limited to about 2 GB of RAM even if your system has more RAM. (Sometimes, you can reach 2-3.5 GB RAM when running a 32-bit executable on a 64-bit operating system, but the memory will be split into two regions, and a single array cannot span two regions – see RAM and Memory.) Since SIMION RAM usage in bytes is approximately 10 times the number of PA grid points, 32-bit versions of SIMION are limited to PA array sizes of around 200 million points.

On a 64-bit system, you are not limited by the above restriction. For example, a system with 16 GB of RAM, 14 GB of which is free, can use a 1.5 billion point array.

Huge array (16GB-190GB) Support: SIMION versions >= 8.1.0.30 support PA files up to 190 GB (about 20 billion points) on Windows (7 Professional/2008/2008R2) if your system has enough RAM to load them. SIMION versions 8.1.0.0-8.1.0.22 only supported 16 GB per PA file. Note: Remote access to 68 GB RAM systems can currently be rented for at most a few dollars per hour on Amazon EC2 “high memory instances” (see SIMION on Amazon EC2).

See RAM and Memory for more details.