Apple: Difference between revisions

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* An upgradeable, swappable SSD in the 2024 Mac Mini - albeit you cannot swap these units between M4 and M4 Pro units due to the internal casing's design being different without much good reason.<sup>Sources?</sup>

* A battery removable with just a 9V battery in the 2024 iPhone 16 and 16 Plus.<sup>Source?</sup>

==== OS downgrades ====

It is not possible to upgrade or downgrade an iPhone, iPad, Apple TV, etc. to an OS version other than the absolute latest. On Macs with T2 chip or Apple Silicon, the user can select from three modes of secure boot:<ref>https://support.apple.com/102522</ref>

* No security: Allow any OS to run (same as turning off secure boot on a PC)

* Medium security: Allow any OS that is signed with a secure boot certificate (default, same as turning on secure boot on a PC)

* Full security: Only allow the latest version of macOS, do not allow any other OS

iOS devices only support full security mode. The device checks for a cryptographic "[https://theapplewiki.com/wiki/APTicket ticket]", which are tied to the OS version and CPU serial number. These are provided by a server, which only provides them for the latest version (with very specific exceptions). The device refuses to boot if the ticket does not match. [https://theapplewiki.com/wiki/Firmware_downgrading Workarounds] exist, but with major caveats that are not viable for most users.<ref>https://en.wikipedia.org/wiki/SHSH_blob</ref>

Users often complain of new OS versions slowing down their device. Once a new version is installed, there is no opportunity to go back. This also restricts the user's choice to jailbreak the device, as the latest version naturally has patches for the latest jailbreak exploits. App developers also require access to earlier iOS versions to test that their app works correctly. The alternative, Xcode's iOS Simulator, is not a complete replacement for real hardware, as it does not have all features of a physical device.<ref>https://contextqa.com/test-on-ios-emulators-simulators/</ref> Instead, app developers are forced to purchase several test devices, and remember to ''never'' allow them to update.

== References ==

[[Category:Companies]]

@@ Line 14: / Line 14: @@
 * An upgradeable, swappable SSD in the 2024 Mac Mini - albeit you cannot swap these units between M4 and M4 Pro units due to the internal casing's design being different without much good reason.<sup>Sources?</sup>
 * A battery removable with just a 9V battery in the 2024 iPhone 16 and 16 Plus.<sup>Source?</sup>
+==== OS downgrades ====
+It is not possible to upgrade or downgrade an iPhone, iPad, Apple TV, etc. to an OS version other than the absolute latest. On Macs with T2 chip or Apple Silicon, the user can select from three modes of secure boot:<ref>https://support.apple.com/102522</ref>
+* No security: Allow any OS to run (same as turning off secure boot on a PC)
+* Medium security: Allow any OS that is signed with a secure boot certificate (default, same as turning on secure boot on a PC)
+* Full security: Only allow the latest version of macOS, do not allow any other OS
+iOS devices only support full security mode. The device checks for a cryptographic "[https://theapplewiki.com/wiki/APTicket ticket]", which are tied to the OS version and CPU serial number. These are provided by a server, which only provides them for the latest version (with very specific exceptions). The device refuses to boot if the ticket does not match. [https://theapplewiki.com/wiki/Firmware_downgrading Workarounds] exist, but with major caveats that are not viable for most users.<ref>https://en.wikipedia.org/wiki/SHSH_blob</ref>
+Users often complain of new OS versions slowing down their device. Once a new version is installed, there is no opportunity to go back. This also restricts the user's choice to jailbreak the device, as the latest version naturally has patches for the latest jailbreak exploits. App developers also require access to earlier iOS versions to test that their app works correctly. The alternative, Xcode's iOS Simulator, is not a complete replacement for real hardware, as it does not have all features of a physical device.<ref>https://contextqa.com/test-on-ios-emulators-simulators/</ref> Instead, app developers are forced to purchase several test devices, and remember to ''never'' allow them to update.
+== References ==
+<references />
 [[Category:Companies]]