After several installations and reverting back to Mojave (thank you Carbon Copy Cloner!) I finally have Catalina running well (Clover v2.4k r4961) on my B85 Powermac G5 here in Central Ohio. The issues that I ran into were:
No Wifi. When I first installed Catalina I was dismayed to discover that my homebrew Wifi adapter, which uses a real Apple MacPro Airport card, was no longer supported. It took a little bit of research and a lot of trial and error to resolve this issue. It turns out that the IO80211Family.kext used in Catalina removed support for this particular card. However, the Mojave version of this kext could be installed to once again provide support. The trick was to figure out how to install it since Catalina has locked down the root directory. I ended up downloading and installing Hackintool (thanks to Nate8727 and Headkaze!), which has the ability to easily disable the Gatekeeper and mount the disk in read/write mode plus it can install the kext as well. So I copied the kext from my Mojave drive, installed it, and rebooted. Voila! Once again my Wifi was back up and running normally. Whew!
Scrolling. This was a show stopper for me. Scrolling in web pages and programs is buttery smooth in Mojave. It was smooth in Catalina on my 2012 MacBook Pro too, which is much less powerful than my Hackintosh. But it was not smooth in Catalina on the Hack and it took me a while to figure out what was the cause. It turns out that MagicPrefs, a small utility I used to provide a two-finger right click on my Apple bluetooth mouse was the culprit. I did three separate installations before I figured this out, the last using a clone of my MacBook Pro’s drive. When scrolling worked fine on the external drive (with the bluetooth mouse not connected) and then continued to work well when I migrated my Mojave settings—until I enabled MagicPrefs—I knew I’d found the culprit. MagicPrefs is no more but I also lost my convenient two-finger right click. I use this because I often click too far to the right on my Apple mouse and call up the secondary menu rather than the left click I had intended. The Apple default for the right click on an Apple mouse is to Control-left click. This works fine in macOS but it doesn’t work at all in my Parallels Windows 10 virtual computer. Oh well.
Sadly, there is no update to MagicPrefs.
Thunderbird. The problem that I had to sort out with Thunderbird was that unread mail was no longer bold faced. It turns out that Mozilla has no planned fix for this issue. That’s the bad news. The good news is that the add-on “Font and Theme changer” once again works with Thunderbird. That is by far the best solution since I can make the font larger which makes Thunderbird much more useful, plus incoming unread mail is once again bold faced. Woohoo!!
Drive icons. A problem for which I have no answer at this point is that I can no longer use custom icons for my hard and solid state drives. That’s a bummer because it allowed me to spiff up my desktop. Hopefully a workaround will be found so that I can once again have colorful icons.
APFS required. All drives on which Catalina is installed must now be formatted with APFS. Prior to this only SSDs had to be formatted with APFS, hard drives could remain HSF+. There are a couple of negative consequences. The first is that as of Catalina all APFS drives have two volumes, a System volume and a Data volume, which was highly confusing at first. This was not true in Mojave and has been done to add to system security. You only discover this if you’re booted from Mojave and looking at a Catalina drive or when you’re using Disk Utility in Catalina. At first I thought that something was wrong. When in Catalina you only see the system drive so everything looks normal and Carbon Copy Cloning seems simple. But try to clone from one Catalina drive to another while you’re in Mojave and you are destined for certain failure because there’s no way to select both volumes at the same time. Not good!
Parallels Desktop 13 still works. Yes, my virtual Windows 10 installation was definitely a bit wonky the first time I fired it up, but after I sorted everything out and exited from Coherence and reentered it a couple of times all seemed normal. I’ll eventually upgrade to Parallels Desktop 15 in the near future ($49) but at least I don’t have to do it immediately.