原帖由： Soup ,
This one’s kind of complicated because of the SSD upgrade you plan to do, you may just want get a bootable USB stick of El Capitan to install on both of the machines. As for upgrading the OS on the HDD, all you need to do is click on the Apple Logo at the top left side of the screen, click on software update, and let it download the updates. After that, click on “Show more” and make sure it doesn’t install the Airport of iLife Updates, as it will not be able to update if you try to install those. You may need to repeat that step a couple of times to make sure Snow Leopard is fully up to date, but when it is follow this link on Safari while on the machine: https://apps.apple.com/app/os-x-el-capitan/id1147835434?mt=12 This link should take you to El Capitan’s download page on the App Store, from there all you need to do is download and install El Capitan. If you need more App Support after that, I recommend using the MacOS Catalina patcher, which walks you through and lets you install Catalina on unsupported machines, and because of your 8gb of ram it will be able to handle itself well in Catalina. Here’s the link to the patcher: http://dosdude1.com/catalina/ I hope this helped!