The A12Z has four high performance cores. It is the A13 that has two cores. I agree that we will not see more than 12 core this year but it will be sufficient for the rumored Macs including the 24 inch iMac if it arrives.
What is strange is that we consider iPhone and iPad chip in he Mac line. Most people would have laughed if you said that the next Mac/MacOS will run on a iPhone/iPad chip. Well slightly modified.
Unless you are running high end games, I think many of the coprocessors will offload the GPU. I would not be surprised if a node shrink and slightly larger chip allows for three times as many GPU cores for the iMac 24 (I assume 4K) but it is unclear if it is needed. iPad Pro has 5.6 Mpixels and runs at 120 Hz without issues (8 core GPU). A 4K screen at 8.6 MPixels at 120 Hz seem to be easily achieved with more GPU cores (16?) and that high speed GPU cache.
Apologies, you're right there. 4+4 for A12z - half asleep when I wrote that.
So 2+4 (iPhone equivalent) for 12" and maybe even MBA; 4+4 for 13" MBP/Mini, 8+4 for 16", Mini, and iMac.
And I think that Apple Silicon will have their own 'letter' as far as Apple are concerned so people can't immediately dismiss a Mac running an 'iPhone CPU'. They could start with an M1 cpu for example, and name an M1x or M1z for extra graphics cores.
All this offloading to custom processors does start to remind me of the old Amiga days when there was a variety of co-processors designed to do a job: Agnus for memory control(?), Denise for video, Paula for audio.
This is brilliant, of course, and may lead us to specific specialisations where the Apple Silicon could kill Intel in benchmarks - HEVC encoding for example. I really do look forward to FCPX benchmarks on that basis.
Those of us who remember that the 68000 CPU in the Amiga ran at a downclocked 7.14MHz (for reasons of syncing with video refreshes if I recall) may also remember that Atari ST ports ran slower because the ST had an 8MHz 68000 but no co-processors for graphics or sound so you had situations where games would be ported over and run *slower* on the Amiga because they didn't use the superior graphics and sound capabilities. Later on games would be hamstrung by PCs which used a
planar bitmap which helped a lot on 3D games whereas the Amiga used '
chunky' graphics which helped a lot on scrolling games.
All of this will be built into the existing Apple silicon though, I expect the T2 feature set (reportedly based on the A10) to be rolled into the future Apple silicon - maybe even having some of the efficiency cores do that job?
What Apple have to be aware of is lazy porting of games from ARM systems in the medium to long term future (I'm thinking tablet and Windows for ARM). If Apple aren't producing the highest performing CPUs then they might get left behind again. I would say the best way to do this is to have an in-house AAA team lead with exclusive games - it doesn't have to be Bungie but could be one hell of a story if it was.
If loads of software houses are already predicting iPad/Mac games in the future, rather than coming to iOS/macOS only when Windows on ARM becomes popular I think that would be repeating a mistake - I dare say Apple wants coders to code for Apple Silicon first rather than try and port across later as an afterthought.
As I may have mentioned before, the divergence for Apple silicon will clearly be with extra graphics capabilities and high performance cores for Macs depending on the performance/cooling profile required. At the low end there's clearly a high efficiency benefit to use something similar to what Apple have for the iPhone/iPad already but clearly we'll see what Apple can do when they pile on the high performance cores.