Large-Address-Aware (LAA) programs

Programs (EXE files) provided by or with GEMPACK are of two main types:

However, 32-bit programs also run fine (or maybe better) on 64-bit Windows.

The 2GB limit

32-bit Windows does not allow any one program to use more than 2GB of memory. Very large models (such as 57-good, 100-region GTAP) require more than this. You might be unable to solve such a large model, or you might find that AnalyseGE was unable to load a solution file.

However, some specially-configured 32-bit programs, called 'Large-Address-Aware' (LAA) are able to use up to 4GB of memory, if run under 64-bit Windows. Under 32-bit Windows, these programs can still use only 2GB.

These limits are summarized by the table below:

  32-bit Windows OS 64-bit Windows OS
Standard 32-bit program 2GB 2GB
LAA 32-bit program 2GB 4GB
64-bit program will not run Limited only by
physical RAM
Total memory for
all running programs
3.5GB Limited only by
physical RAM

Since GEMPACK Release 10.0-002 (April 2010), most of the 32-bit program EXE files shipped with GEMPACK are 'Large-Address-Aware'. The converted programs include key GUI programs such as ViewHAR, AnalyseGE and Viewsol, as well as all of the Fortran-based command-line programs used by the 32-bit Executable-Image version of GEMPACK. As well, compile options for source-code GEMPACK users who use the 32-bit Intel compiler cause EXE files which they produce (at install time and later) to be 'Large-Address-Aware'. The effect is to double the memory accessible (from 2 to 4GB) to these 32-bit programs if run under 64-bit Windows and if your PC has at least 4GB of RAM.

ViewHAR and other GUI programs have a Help..About/Diagnostics command which produces a diagnostics file. Line 6 of that file reads:
File: c:\gp\viewhar.exe isLAA Win32
if that ViewHAR.exe is of the newer, LAA, type.

Related topics:
Should I move to 64-bit Windows?
64-bit computing and parallel computations with GEMPACK 10
Not Enough Memory to Solve a Model
Memory Limit for GEMPACK

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