Apple silicon and Intel Macs: what still differs
· 6 min read
The Intel to Apple silicon transition is far enough along that most software works on both. What is left is a set of specific differences that surface when you are installing something unusual, running another operating system, or trying to start a machine that will not boot.
Telling what you have
The obvious route: Apple menu, About This Mac. It names the chip.
From the command line it is less obvious than it looks, because the shell can lie to you:
uname -m
On a real machine that command returned x86_64 while the chip was an Apple M1 Pro. The reason is Rosetta: if the terminal or the shell is running translated, it reports the architecture it is emulating rather than the hardware.
The reliable checks:
sysctl -n hw.optional.arm64 # 1 on Apple silicon
sysctl -n sysctl.proc_translated # 1 if this process is under Rosetta
sysctl -n machdep.cpu.brand_string # names the chip
On the machine above those returned 1, 1, and Apple M1 Pro respectively. So it is Apple silicon, and the shell was translated.
This matters more than it sounds. Package managers and build tools read uname and will happily install Intel binaries on an Apple silicon Mac, which then run under translation and slower. If software you installed feels sluggish, check whether your terminal is running translated.
Rosetta
Rosetta 2 translates Intel software to run on Apple silicon. It is installed on demand the first time something needs it, and it is good: most Intel applications run at a speed people do not notice.
Where it shows is in sustained heavy work, and in anything that needs to load Intel and native code into the same process, which does not work. That last point is why some plugin-based applications had a long transition.
You can force an application to run under Rosetta: right-click it in Applications, Get Info, and tick Open using Rosetta. Occasionally useful for an application whose plugins are Intel-only.
Virtualisation, which is the real difference
An Intel Mac can run Intel Windows and Intel Linux in a virtual machine, because the architecture matches. It can also run Boot Camp.
An Apple silicon Mac cannot do either. What it can do is run ARM versions of Windows and Linux in a virtual machine, which works well and is not the same thing. Software inside that Windows which requires Intel will not run, or will run under Windows’ own translation with mixed results.
Boot Camp does not exist on Apple silicon and will not return.
If you depend on running Intel Windows software, that is the single biggest remaining consideration when choosing a machine.
Starting up and recovery
The key combinations differ, and this is where people get stuck at exactly the wrong moment.
Intel: hold Command-R at startup for Recovery, Option for the startup disk picker, Command-Option-P-R to reset NVRAM.
Apple silicon: hold the power button until “Loading startup options” appears. Everything, including Recovery, is behind that one gesture. There is no separate key combination, and NVRAM reset is not a user-facing operation.
What Recovery Mode is covers both.
Target Disk Mode also changed: on Apple silicon it is Share Disk, reached through the same startup options, and it behaves differently. Target Disk Mode and its modern replacement covers it.
Memory works differently
Apple silicon uses unified memory shared between the processor and graphics. That is genuinely more efficient, and it means the number is not comparable with an Intel Mac’s RAM figure plus separate video memory.
The practical consequence: 16 GB on Apple silicon goes further than 16 GB on an Intel Mac did. It is not double, and the comparison is not one to one. How much RAM a Mac actually needs covers picking a figure.
It also cannot be upgraded, which was already true of most recent Intel Macs.
What has not changed
macOS behaves the same. Files, settings, iCloud, migration between the two directions all work. Migration Assistant moves from Intel to Apple silicon without difficulty, and applications come across, though reinstalling them gets you native versions.
External devices, displays and peripherals work the same, with the caveat that some older drivers written as kernel extensions do not load on Apple silicon and need a modern replacement from the vendor.
Questions
Should I still buy an Intel Mac? Only if you specifically need Boot Camp or Intel virtualisation. Otherwise no; Apple silicon is faster, cooler and better supported going forward.
Will my old software keep working? Most does, through Rosetta. Very old software written for even earlier architectures does not, and anything relying on kernel extensions may need replacing.
How do I know if an app is running natively? Activity Monitor has a Kind column showing Apple or Intel. Add it from the View menu.
Is Rosetta going away? Apple has removed translation layers before, after several years. Nothing is announced, and it is reasonable to prefer native versions where they exist.