High Sierra or Mojave on M1 ?

[Dr. McKay]

I currently have a 27 inch iMac i5 (2017 model), a 2015 Macbook Pro i7 and an iPhone 8 Plus. Had an iPad Pro 12.9 inch 2ng gen, but sold that last week, no longer have a need for it (frustrated when having to type stuff on it and so I always ended up doing it the MBP anyway).

I'd like to simplify my setup and do a little upgrade in the process. I'm a translator so mostlly work with text and I also do some occasional graphic work when integrating said text into catalogues for print and web ; i.e. some light Indesign/Illustrator/Photoshop work, no heavy lifting.
The company I work for requires me to still have Mac OS High Sierra or Mojave on an external SSD drive which I boot from and then connect via VPN when working from home (we use database software that's still 32 bit so any Mac OS from Catalina and up is out of the question - software will be upgraded in late 2022).
I also need Windows 10 to drive the software of my girlfriend's laser cutting/engraving machine (mac version on the way, but still a long way off).
On both my Intel Macs, that's no problem at all (both the iMac and MBP still run High Sierra 'officially').

Now, to simplify my setup, I have been looking at the Macbook Air M, to replace both the iMac and MBP, and get a nice external 1440p IPS display for my home office ; I'd go for a regular iPhone 13 to replace the 8 Plus.

So, the Macbook Air M1 : after watching numerous reviews, it's clear that this machine is plenty fast and would suit me for years to come (I'd go for the 8-core model, 512gb SSD and 16Gb of RAM).
Running Windows on it would be no problem with Parallels (I'm willing to invest in that), I've tested yesterday, all good (of course, tested on Intel but numerous Youtube videos says it works flawlessly on M1 as well).

However, running High Sierra or Mojave may prove to be more of a hassle...
To create the external SSD, I downloaded the High Sierra disk image from the App Store, installed it and never had any issues with it.
Yesterday, on the iMac running Monterey, I tried using that same disk image to install High Sierra using that same Parallels trial I had used to install Win10. The install starts normally, but on the recovery screen (where you can choose to install or do a Time Machine recovery) I get the message that the disk image is damaged. Tried the same with a Mojave image, same thing.
And that's on an Intel Mac.

I need to be sure that I can still run High Sierra (or Mojave) until late 2022 on the M1 MB Air or I won't be able to do my job.
Any advice ? Could it be a Parallels issue ?
If there's no solution, I'll have no choice but to wait until late 2022 to 'upgrade and simplify'...

 

[Mike Boreham]

I currently have a 27 inch iMac i5 (2017 model), a 2015 Macbook Pro i7 and an iPhone 8 Plus. Had an iPad Pro 12.9 inch 2ng gen, but sold that last week, no longer have a need for it (frustrated when having to type stuff on it and so I always ended up doing it the MBP anyway).

I'd like to simplify my setup and do a little upgrade in the process. I'm a translator so mostlly work with text and I also do some occasional graphic work when integrating said text into catalogues for print and web ; i.e. some light Indesign/Illustrator/Photoshop work, no heavy lifting.
The company I work for requires me to still have Mac OS High Sierra or Mojave on an external SSD drive which I boot from and then connect via VPN when working from home (we use database software that's still 32 bit so any Mac OS from Catalina and up is out of the question - software will be upgraded in late 2022).
I also need Windows 10 to drive the software of my girlfriend's laser cutting/engraving machine (mac version on the way, but still a long way off).
On both my Intel Macs, that's no problem at all (both the iMac and MBP still run High Sierra 'officially').

Now, to simplify my setup, I have been looking at the Macbook Air M, to replace both the iMac and MBP, and get a nice external 1440p IPS display for my home office ; I'd go for a regular iPhone 13 to replace the 8 Plus.

So, the Macbook Air M1 : after watching numerous reviews, it's clear that this machine is plenty fast and would suit me for years to come (I'd go for the 8-core model, 512gb SSD and 16Gb of RAM).
Running Windows on it would be no problem with Parallels (I'm willing to invest in that), I've tested yesterday, all good (of course, tested on Intel but numerous Youtube videos says it works flawlessly on M1 as well).

However, running High Sierra or Mojave may prove to be more of a hassle...
To create the external SSD, I downloaded the High Sierra disk image from the App Store, installed it and never had any issues with it.
Yesterday, on the iMac running Monterey, I tried using that same disk image to install High Sierra using that same Parallels trial I had used to install Win10. The install starts normally, but on the recovery screen (where you can choose to install or do a Time Machine recovery) I get the message that the disk image is damaged. Tried the same with a Mojave image, same thing.
And that's on an Intel Mac.

I need to be sure that I can still run High Sierra (or Mojave) until late 2022 on the M1 MB Air or I won't be able to do my job.
Any advice ? Could it be a Parallels issue ?
If there's no solution, I'll have no choice but to wait until late 2022 to 'upgrade and simplify'...

Sorry. You will not be able to run Mojave or High Sierra on an M1 Mac, internally or externally. The first ARM macOS version was Big Sur. Mojave and High Sierra also cannot be run in a Parallels Virtual Machine on an M1 Mac.

 

[Dr. McKay]

I was afraid of that...
Oh well, guess I'll wait another year.

 

[DeltaMac]

hmm... Can you run the translaton software on Windows (through Parallels)?
Or is that software for macOS only?

 

[Fishrrman]

OP:
"The company I work for requires me to still have Mac OS High Sierra or Mojave on an external SSD drive which I boot from and then connect via VPN when working from home (we use database software that's still 32 bit so any Mac OS from Catalina and up is out of the question - software will be upgraded in late 2022).
I also need Windows 10 to drive the software of my girlfriend's laser cutting/engraving machine (mac version on the way, but still a long way off).
On both my Intel Macs, that's no problem at all"

I'll say it plainly:
An m-series Mac (m1, m1pro, m1max) IS NOT FOR YOU.
It's not going to work.

You can't boot the m-series from either High Sierra or Mojave.
Cannot be done.
These require at least Big Sur from which to boot.

Re:
"guess I'll wait another year."

Things aren't likely to change in your favor.
New Macs will never run 32 bit software again.
You had best look for another solution.

 

[DeltaMac]

OP:
...

Re:
"guess I'll wait another year."

Things aren't likely to change in your favor.
New Macs will never run 32 bit software again.
You had best look for another solution.

OP did say in Post #1 that they expect an upgrade (I assume that means 64-bit) of the software in late 2022, so that's where the year wait comes from.

 

[Dr. McKay]

OP:
"The company I work for requires me to still have Mac OS High Sierra or Mojave on an external SSD drive which I boot from and then connect via VPN when working from home (we use database software that's still 32 bit so any Mac OS from Catalina and up is out of the question - software will be upgraded in late 2022).
I also need Windows 10 to drive the software of my girlfriend's laser cutting/engraving machine (mac version on the way, but still a long way off).
On both my Intel Macs, that's no problem at all"

I'll say it plainly:
An m-series Mac (m1, m1pro, m1max) IS NOT FOR YOU.
It's not going to work.

You can't boot the m-series from either High Sierra or Mojave.
Cannot be done.
These require at least Big Sur from which to boot.

Re:
"guess I'll wait another year."

Things aren't likely to change in your favor.
New Macs will never run 32 bit software again.
You had best look for another solution.

I didn't expect to be able boot natively into High Sierra or Mojave on a M1 Mac, I just assumed it might be possible to run High Sierra/Mojave using Parallels (or any other virtualization software) on the M1.
In any case, the 32-bit mac client of the software we currently use will be replaced next year with something browser based so when that happens, it won't matter what platform I'm on in order to access it.