AutoCAD 32-bit maintains binary compatibility with existing 32-bit ObjectARX applications. 32-bit applications load in binary form, and they still build and link without errors using the ObjectARX for AutoCAD 2021 API.
To run in the 64-bit AutoCAD process, native 32-bit applications must be ported to 64-bits. This requirement includes ObjectARX and COM/ObjectARX DLLs. While your applications may present internal porting issues, ObjectARX API usage does not change in the 64-bit environment. However, you must substitute the proper polymorphic types in ObjectARX calls that may be sensitive to 64-bit porting concerns.
The following table indicates the type of porting effort, if any, required for various types of AutoCAD applications.
| AutoCAD Application Type | Portability to 64-Bit Platform |
|---|---|
| Native ObjectARX applications (.arx and .dbx files) | Requires porting to 64-bits, but no changes in API usage |
| Managed applications | Binaries are platform independent |
| COM ObjectARX DLLs (in-process) | Requires porting to 64-bits, but no changes in API usage |
| COM EXEs (out-of-process) | Requires porting to 64-bits. Mixing platforms will cause issues. |
| Visual LISP LSP files | No changes |
| Visual LISP compiled FAS files | No changes; the FAS file format is platform independent. |
| VBA (DVB files, macros in DWG files) | Supported on 64-bit platform via an out-of-process proxy application |