Risc Os on Mac Arm ?

Perhaps, but the article I just read called it an emulator. We’ll see.

It translates the binary on first launch. Apparently more complex apps can sit and bounce in the dock for quite some time at first!

@ Clive

Another issue from my point view – how many of the 3rd party apps I use on my Mac Mini will be available on the ARM-based Mac Mini?

YES

Apparently there’s an emulator that’ll run the old intel apps. They call it Rosetta 2.

Yes Rosetta 2 is not an emulator, it’s a Binary Translator that translate x86_64 into AArch64 at installation time, so your application will be executed as native ARM64 code

Previous version was called just Rosetta and it was always a binary translator (from PowerPC binary to x86), however it did BT in JIT fashion (Just In Time, aka at runtime) and that was slow, so Rosetta 2 does the same but at installation time, one time only.

Also on top of that new compilers support what is called Universal Binary, which is a binary file that contains both ARM64 and x86_64 code, the OS loader uses the UB metadata to find the entry-point to the correct binary.

UB executes immediately and no need for translation at installation time or JIT, while original x86_64 binaries gets translated into ARM64 at installation time. With new releases of the apps you use they will all come in UB format.

@ Chris Mahoney

It translates the binary on first launch. Apparently more complex apps can sit and bounce in the dock for quite some time at first!

Correct, when I installed XCode on my DTK it took like an hour to install it and translate it from x86_64 to ARM64…

There’s a fun thread on Twitter comparing the ARM1 (25 thousand transistors) with Apple’s M1 (16 billion transistors!) – https://twitter.com/kenshirriff/status/1327021630636212224

Several replies pointing out a better comparison is the ARM250 as they are both a System On Chip, but I don’t think that would change the difference in scale much.

Paolo: Many thanks. Interesting.

Sadly my budget won’t currently stretch to the £699 price of the new Mac Mini – the odd thing is that recent high-end Mac Minis with Intel chips are selling for more than that 2nd hand!

no microcode

By that measure, is any ARM a RISC? Even ARM1 has microcode and micro-operations to an extent: http://www.righto.com/2016/02/reverse-engineering-arm1-processors.html

And modern ones are, as far as I’m aware, quite a bit more heavily microcoded. (Granted, likely not as dependent on it as a CISC, but. Doesn’t help that there’s five ISAs that an AArch64 processor could hypothetically have to “execute” (AArch32, Thumb, Jazelle, ThumbEE, and AArch64), with varying instruction widths (Thumb 2 even having variable instruction width within the ISA). Wouldn’t be surprised if that’s part of why Apple dropped AArch32, and why ARM is phasing out AArch32 from big cores, so they could drop Thumb/ThumbEE and whatever stubs for Jazelle were left around and simplify/speed up their decoders.)