# When using OdCopyEx.cpp to convert the CAD file version, the out of memory dialog box pops up, and the code throws an exception when readFile.

 1. [FAQ](/faq)
2. »
3. [Examples](/faq/examples)

Dwg file format is highly compressed and drawing occupied much more memory than file size.  
Memory limit for 32-bit application is 2G. 64-bit application has no such limitation.  
In some scenarios partial loading and paging can reduce memory usage but saving drawing to file require that all data is loaded into memory.