Actually it is a hard question to answer. Simply because we have different versions of both the image, firmware application running on the image as well as the Xamarin Addin/DLL. Currently the version of the of the image is 1.0, the latest firmware running on the image is 1.0 while the Xamarin Addin/DLL has version 1.1 this can be read from the following URL. The idea behind this setup is that we can release a new firmware without users needing to download and create an entire image – you simply download a new firmware application. When you check for updates the following logic is executed.
1. If your image version is different from the the version in the link above you will get a notification/message that tells you a new image is available. And the next step will not be executed.
2. If however your image is up to date but a new firmware application is available you will be asked to download the application. If the firmware is not up to date the next step will not be executed until the firmware has been updated.
3. If you are using the Xamarin Addin it will write a version stamp when a program is uploaded to the brick. This version number in this stamp will be compared to the one in the link above.
Sometime in the future we will add support for comparing the DLL used in the program that has been uploaded to the EV3 with the link/current version.
So to see if your system is up to date simply compare the version of your Image, firmware and Xamarin Addin with the version of the found in the link.
Please note that some of the fist releases of the MonoBrick image only tells you if new software is available it does not distinguishing between image and firmware. In that case you should download a new image.
I know that this information is not available anywhere and I apologize for this – I have been dying to write a tutorial page on updating the system but just haven’t had the time. Maybe I will use this answer as a starting point.
Anyway hope this answers your question.