ARM64, also frequently called AArch64, is the 64-bit processor architecture designed and licensed by ARM Holdings. The Apple silicon family of processors in Macs (M1, etc.) and the processors in every modern iPad and iPhone, as well as Windows 11/10 PCs that have ARM processors rather than Intel or AMD x86 (and now x64) processors, as most Windows PCs have been since Windows first shipped.

I use that naming for two reasons. One, it’s what Apple calls their family of processors on ARM-based Macs. Two, because there are the original set of M1 Macs and a whole new cadre of Macs with M1 Pro and M1 Max, and surely future Mx variants… so just using the generic “Apple silicon” nomenclature (note small “s”, as Apple indicates), I can speak to the whole family of future Macs, not just the first generation of ARM64 Macs/processors.

“Windows on ARM” is the nomenclature that Microsoft uses to describe Windows that is designed, tested, released, and supported on new ARM-based Windows PCs that it is sold with. This name is to simply denote when one is talking about Windows, which has primarily run on Intel/AMD processors since it first shipped, versus Windows designed for 64-bit ARM processors like those in new Qualcomm-based Windows PCs or Apple silicon Macs.

You can currently run Windows 10 or Windows 11 on an Apple silicon Mac. Since this is just virtualizing the Mac’s own 64-bit ARM processor, you must also use “Windows on ARM”, the ARM64 release of Windows that Microsoft has specifically designed and released for Windows PCs with 64-bit ARM processors.

Windows 11. You should choose Windows 11, not because of the support lifecycle or any specific reason other than the fact that Windows 11 now includes the ability to emulate both 64-bit and 32-bit Intel instructions. Less nerd-speak – most of your existing applications will just work on Windows on ARM, even if the vendor hasn’t updated them to run natively on Windows on ARM. On Windows 10, only 32-bit emulation was ever officially released, meaning many newer applications can’t run on Windows on ARM unless they’re modified to be compatible.

No. Prior to Windows 10, Microsoft did not support Windows running on a 64-bit ARM processor like the chips in a current Windows on ARM PC or an Apple silicon Mac. While it’s conceptually possible that you could get Windows 8.1 or earlier running using QEMU/UTM, you will pay a significant performance penalty to do so, since the VM will be relying on costly emulation of an Intel processor, not virtualization of the Mac’s own ARM64 processor.

No, and we need to get you a new hobby. Windows RT only supported a range of 32-bit ARM processors, and the OS is completely unsupported and effectively useless.

No. If you’ve used Parallels or VMware in the past on a Mac or a Windows PC, you were virtualizing Intel hardware on an Intel-based Mac or PC. This means the installation of Windows—the software running inside of that VM—is only capable of ever running on another Intel-based Mac or Windows PC.

No. There is no magical incantation, utility, or hack that you can use to transmogrify an existing Intel-based Windows installation into an installation of Windows on ARM. You must create entirely new virtual machines, which will not work on any Intel-based Macs or PCs.

There isn’t one. You will need to reinstall those application in the new VM. There is no method I’m aware of—and definitely no method I’d personally trust—to migrate, move, or transfer those existing applications to a new VM.

You don’t. At least not at a store or online as something called that. However, thanks to Microsoft clarifying the rules a bit as discussed in my last blog post, it’s now understood that you can buy a license for Windows 11/10 from Microsoft online, and use that product key to activate your virtualized Windows on ARM install (the OS is most likely put in place by Parallels itself).

Yes. Microsoft has complex rules that govern how Windows Enterprise edition is licensed in particular. These rules have always affected Intel-based Macs, since they can run Windows as well. Microsoft has clarified that the rules are identical for Apple silicon Macs. This is complete licensing nerd-porn, but it’s important for business customers to know.

Unclear. If Windows is running unreliably in a VM on your Apple silicon Mac, it’s pretty clear that your first point of contact is your hypervisor vendor (most likely Parallels) and possibly Apple, but that’s most likely Parallels’ escalation to make, not yours as a consumer. (This could include VMware or other virtualization vendors if they officially endorse/support Windows on ARM running on Apple silicon.)

Nope. See the FAQ above. If you have an issue with Windows on an Apple silicon Mac, I fully expect that Microsoft will reply in many/most/all cases with “Does the same issue occur when running Windows on ARM on a Qualcomm-based PC sold with that OS?” They might investigate. They might fix it if it’s actually an issue with Windows, Office, or other Microsoft software. But most likely it’s an issue for your virtualization vendor or Apple to resolve.

Unclear. Because Windows on ARM is still in this weird primordial stage where it feels like more of a hobby than Apple’s move full-speed towards ARM64, a lot of software and hardware vendors are still on the fence about supporting the platform. If you have a line-of-business application, you’re likely on your own. Your first step is, like the FAQ above, test the application and see if it works on Windows on ARM running on a Qualcomm PC that shipped with that OS. Software and hardware vendors could justifiably say it’s not their problem until you’ve ratified that that doesn’t work either.

Unclear. You can contact your hardware vendor, but because you’re running Windows in a VM on an Apple silicon Mac, they may also prove resistant to helping resolve this issue unless you can reproduce it on a Windows on ARM PC, and they support that platform.