OpenROAD for UNIX or Linux includes MainWin components. The MainWin product (by Harmon.ie) provides the infrastructure necessary to use Microsoft's COM and to access the Windows registry on UNIX or Linux platforms by running a collection of user-specific services that implement this central Windows system functionality.

The processes mwrpcss and regss can be started and stopped manually for each user by using the "mwadm start" and "mwadm stop" commands, respectively. If OpenROAD is used while the processes are not running, they will be started automatically.

The MainWin System Core is not used on 64-bit UNIX or Linux systems, although some MainWin components are included. 64-bit versions of OpenROAD for UNIX/Linux include MainWin components.