That should work just fine since the old macOS you need is Sequoia and your M1 MBP supports that macOS. Multiple macOS versions on the same drive (internal or external) can get a bit confusing (eg. an internal SSD with at least 10 volumes spread over at least two groups), but there’s good documentation (see below) to help with that. Keep in mind that if you decide to install one version of macOS on an external drive, for that initial install to work, the drive may NOT be connected to your Mac’s DFU port.
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Yes. Dual-boot is installing multiple operating systems on the computer (whether on internal or external storage). You will boot the computer with one of them, and the others don’t do anything. To switch between them, you need to reboot the computer.
Virtualization and emulation are mechanisms for running another operating system at the same time as the computer’s primary operating system.
- Emulation uses software to duplicate (that is, emulate) the behavior of all of a computer’s hardware (CPU, peripherals, etc.). It is the mechanism usually used to (for example) run an Intel version of Windows or a PowerPC version of macOS on an Apple Silicon Mac.
- Virtualization does not emulate the processor, may not emulate connected peripherals either. It runs the virtualized operating system on your CPU like an application, using a variety of (usually hardware-assisted) techniques to keep the virtual system isolated from the main system.
Virtualization usually provides better performance, but it can only run operating systems compatible with the host system’s hardware architecture. Emulation will let you run completely incompatible software, at the expense of a significant loss of performance.
It should be possible. For a dual-boot solution, you can download the Tahoe installer, boot into Recovery mode and install it to a new set of volumes on your SSD or to an external SSD. I haven’t done this, but here’s an Apple support article about how to install macOS on external storage devices:
Virtualization is also an option. You will need to get a suitable VM platform. I don’t know if all can virtualize macOS, but I do know about this one (from Howard Oakley):
I know about three other VM platforms (VMWare Fusion, Parallels Desktop and VirtualBox), but I don’t know if or how well they can run macOS in a VM on Apple Silicon.
Regardless of which VM platform you choose, you will create a virtual disk (a large multi-GB file used to emulate a storage device for the VM) and you will install macOS onto that virtual disk.
Of course, if you need FireWire access, it limits your options. You’ll need one of:
- Dual-boot. Boot into macOS 15 when you need to access FW. Boot back into macOS 26 otherwise.
- VM with a macOS 15 host. Boot macOS 15 and run 26 in a VM. Of course, this will limit some of 26’s capabilities.
You will not be able to use a macOS 26 host, running 15 in a VM. Although you should be able to get macOS working, it will almost certainly not be able to access a FW device.
USB will definitely work (but you’re right that USB 2.0 will be slower than FW).
There are eSATA-USB adapters. I don’t know how well they work.
Also, depending on the drive, you may be able to remove the drive from its enclosure and put it in a modern USB3 enclosure. This may not work for all drives - some external drive manufacturers use drives with custom firmware, making them incompatible with anyone else’s enclosures. But if it works, that’s a good way to upgrade the interface.
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Apple states dual-booting is temporary.
I had saved a bookmark to a very similar Apple support page which is a few weeks older than the page David C. linked to. There Apple states that a dual-boot setup is only a temporary solution, particularly when maintaining an older system version. This is due to changes introduced by ongoing updates to the new OS for security etc. which potentially conflict with the older OS.
Yes, they state (on the page you linked to, emphasis mine):
The section I emboldened explains why. Basically, they’re saying that future macOS releases may install firmware updates to various components (e.g. an Intel Mac’s T2, a Wi-Fi module, the pre-boot system, etc.) that are incompatible with old versions of macOS.
We know they already did this once. Apple changed the organization of the non-macOS APFS containers when moving from version 11 (Big Sur) to 12 (Monterey). The new organization pretty much breaks Big Sur installations, making dual-boot difficult if not impossible.
In other words, I don’t think they’re saying that they plan on eliminating dual boot capability, but it’s not a viable approach for keeping an old version of macOS (e.g. version 12 or 13) running into the indefinite future. If you want to do that, you’ll pretty much need to dedicate a computer to the task or see if you can do it through emulation (which should eliminate any dependencies on the host OS installation).
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I agree with David. Apple’s approach to OS management is almost entirely forward-looking, as opposed to legacy support. If I am not mistaken, the last Macs with actual FireWire ports were released in 2012.
If your needs are occasional and Mojave or Catalina will suffice, a mid-2012 MacBook Pro with an SSD will do very nicely, as will an SSD-equipped 2012 Mac mini. Of course, many newer machines will work with the right set of adapters.
Depending on the application, you may even find a current Windows 11 desktop to be a suitable host for a FireWire device, but you need to do a little research to ensure that any third party FireWire card you add to the machine will work in Windows 11. Apparently, many cards work using legacy drivers, but some don’t.
What is the chance of third party drivers? I very rarely use FW now days but I have an OWC Thunderbolt dock with FW and some peripherals. It’s not a big loss but a bit annoying.
Doubtful:
- There isn’t a lot of demand for FW support. So there aren’t likely to be many people with the skills and desire to develop such a driver.
- Although it may be possible to develop a driver for Darwin (the Unix platform on which macOS is based), Apple has very strict rules for what kind of kernel drivers they will authorize/sign, and unsigned drivers get blocked by macOS’s security model.
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Sad to see my old OWC and Glyph drives go into retirement. Amazing how durable and reliable they’ve been. At least some of them had USB ports and piggybacking them got to be problematic for reasons I never figured out.
“Piggybacking?” I’m unfamiliar with that term.
I guess I am relieved I kept my Mac Mini (worked fine prior to Mac Studio upgrade) in a box. Along with an OWC Thunderbolt dock, I have an LaCie Optical DVD-RAM drive that the media I have, I didn’t catalog, I’ll wait till I retire and fire “pun” them up and realize maybe a good thing or maybe waste of time and storage. Even have brand new, never used DVDRAM carts.
But this points out the failure for Apple to not permit Virtual Machines to interface with archival legacy media, but instead, risk to keep older machines on a shelf for purpose to network or sneakernet anything relevant to access that isn’t supported.
Funny. I kept a Powermac G3 (beige) incase I ever needed OS9 to 10 stuff. Even have that MacSE for dust collection. Guess hoarding macs and adapters is OK…
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