Should Catalyst be installed on a Windows 32-bit or 64-bit operating system?

Prior to version 5.15, Catalyst could be installed on a PC with either a 32-bit or 64-bit Windows operating system. Beginning with version 5.15, Catalyst must be installed on a machine with the 64-bit Windows operating system. 

In addition to the OS, Catalyst required the 32-bit version of Microsoft Access prior to version 5.15. Beginning with version 5.15, Catalyst requires the 64-bit version of Microsoft Access. Since individual Office applications must all be the same version, these requirements extend to all Office applications.

For 32-bit Catalyst versions prior to 5.15, you must use the Access 2010 32-bit version (or later version of Access). The 64-bit versions of Microsoft Office and Access are not compatible with Catalyst. Further, the 32-bit versions of the Access cannot be installed on a machine where Office 64-bit products have already been installed. Microsoft issued knowledgebase article 2269468 recommends installing the 32-bit Office product on machines with 64-bit operating systems to preserve compatibility with 32-bit applications.