Updating firmware on an imac
You can find out more about the system requirements for mac OS here.
Apple says that you need at least 2GB RAM to run Mac OS High Sierra, but this is unlikely to be a problem as all the supported Macs have at least 4GB RAM, and these days most Macs have 8GB as standard, some even have 16GB.
Apple has allegedly stopped development on its Air Port wireless routers in 2016, and to our knowledge, the company does not plan to produce another product in the Air Port family in the near future.
Update: Support documents for the security contents of the 7.7.9 and 7.6.9 updates confirm that the KRACK Wi-Fi vulnerability has been addressed alongside a few other security issues.
So we recommend you hold your horses and do some tidying up and preparation first.Updating your Mac to the latest version of the Mac operating system is really easy, free, and not nearly as time consuming as it used to be.However, there are a few things we recommend you do first to ensure things go smoothly, we run through these, as well as instructions for downloading and installing the latest version of the Mac OS in this tutorial.Apple released KRACK security updates for other devices earlier this year.The new firmware updates can be installed using the Air Port Utility app for i OS or mac OS.