Is iCloud from Catalina backwards compatible with older systems?

[Mac Hammer Fan]

I consider to upgrade my MacBook Pro 2015 to Catalina. However I have two Mac Pro's with older OS: Mojave, High Sierra and even Yosemite. Will my Mail, Notes, Photo's en Agenda still be synchronised on this older machines? I don't use Reminders. As long as iCloud is synchronised on these Macs I am happy.
TIA

 

[Ritsuka]

Mostly. The only new features that won't be compatible are Reminders (but only if you decide to upgrade it to the new format) and iCloud Shared Folders (that won't be available anyway in the first release).

 

[MacDuggy]

I’ve got Catalina installed on a suped up i5 MacBook Pro 2012 (pre Retina) and it runs fine. It was slow as a lame turtle before I replaced the incumbent 500 GB HDD with 1 TB SSD and beefed up the RAM from 4 GB to 8 GB. Not a gamer but pretty quick after the upgrades.