One of the nice things about the Apple ecosystem is that things really work well when you're current. One of the terrible things about the Apple ecosystem is that if you fall off the supported systems list you're left to wither, stumbling around closed-source code and proprietary hardware with no available parts.
Our move to student BYOD was almost a decade ago which means we have some old computer lab hardware laying around such as late-2013 21.5" iMacs. If memory serves, they shipped with Mountain Lion which I think was the last OS X that Apple charged to upgrade. Mavericks was released shortly after we acquired the iMacs and the free upgrade was a nice touch. We opted for the wireless Magic Keyboard and Mouse, deciding to go all-in on the sleek aesthetics. It could have been interference, somebody microwaving their lunch, or our cinder block construction, but having 25 pairs of wireless devices in one room wrecked havoc on connections. Countless hours were wasted reconnecting devices and preventing peripherals from connecting to other iMacs.
As time goes on I'm going more and more portable. My current workflow involves a 13" Macbook and an iPad, but I have two external displays when I'm at my desk. (side note: at the time of me writing this Apple has dropped the term "notebook" and has adopted "laptop.") I still think there's a place for desktop computers, specifically permanent workstations/kiosks or terminals requiring a consistent setup, e.g. server monitors or readouts. Then there's the practicality of having a larger display. I think we're all waiting for the final merge of iPad and iMac by having a shell of a desktop with just a keyboard and mouse and you just slide in an iPad to "dock" it.
I guess this is a long way to say I haven't gotten rid of any old iMacs yet. So after yet another Makerspace reorganization I plugged one in, resynced to Meraki and Apple School Manager and ran all the updates. It took the better part of a day just because of how slow everything was running. It was on Catalina and just needed a big macOS update and some app updates but it was running ok. I then decided to compare it's lacklustre performance to a fresh install of Catalina. While it was installing I tried to upgrade to Monterey but realized it had dropped support to these iMacs, even though they were still Intel-based.
Thankfully, OpenCore allows patching of the bootloader to allow macOS installs on non-native hardware. It was a straightforward process to create a USB boot disk with Monterey get it up and running. OpenCore even detects that it's booting from USB and offers to load it into the HD!
So far Monterey seems slightly faster than a clean install of Catalina. But it still wasn't fast enough so I decided to swap in a $20 SSD and 16GBs RAM -- the RAM was double the cost of the SSD! Getting into the iMac was quite the chore. iFixIt had a nice teardown along with colour-coded screw placement which helped immensely in the rebuild. Some notes:
- using a utility knife with max 3/8" blade length worked well for cutting display adhesive
- cable connections are very fragile! I may have broken off an antenna connector
- the logic board can be screwed in but still offset enough to have the ports not-aligned with the rear cutouts. Triple check all plugs are usable before closing it up
- RAM may be replaceable without removing the logic board but you'll need to be agile enough to release the locking lever by touch alone
- adhesive strips can be found cheap on Aliexpress
