Details of new firmware versions for iMac 2019 models, those with T2 or Apple silicon chips. And how Apple assigns version numbers to iBoot.
Apple silicon
From a simple linear Basic program, or a command tool like tar, to working with macOS to get threads allocated to the most appropriate cores and run at the right frequency.
Step by step through all the features, some undocumented by Apple. Two different Recovery Assistants, Repair Assistant, Erase Mac, Startup Security Utility, change settings and more.
Last September, Tahoe replaced Apple Diagnostics with a new and improved suite of tests for Apple silicon Macs. No one seems to have noticed, least of all Apple.
It’s the percentage of time a core in active, when not idle or shut down. That’s confounded by Intel Hyper-threading, and frequencies of Apple silicon cores.
Apple silicon architecture is designed to get background processes out of the way of our apps running in the foreground, by using the E cores.
One Thunderbolt port is the designated DFU port, to be used when connecting via USB-C in DFU mode, and to be avoided for external bootable disks. But how can you identify it?
You press the Power button, but nothing happens. Has your Mac suddenly died, does it have a problem you can fix easily, or is it just in DFU mode?
After the Boot ROM, LLB and iBoot (stage 2), kernel boot starts setting up security services and putting the hardware to work. CPU cores are started up before file systems are mounted, and the Mac starts userspace boot.
First decide what you want to ‘clean’: the Data or System volume, or firmware? Then consider the methods of choice to perform that. Explained for Intel and Apple silicon Macs.
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