MikroTik has introduced a new feature to their switch devices- dual boot! Starting with their CRS3xx series, you now have the option of choosing which operating system you prefer to use, RouterOS or SwOS.
If you prefer to have a simplified switch only OS with more switch specific features, use SwOS. If you are used to Winbox and would like the ability to use routing and other Layer 3 features on some ports in your CRS, you can boot RouterOS. You will be able to select the desired operating system from RouterOS, from SwOS or from the RouterBoot loader settings.