Zarf Updates

When Apple shipped the first ARM ("Apple Silicon") Macs, they came with Rosetta 2: a tool which allowed existing Intel apps to run on ARM.

One day, Rosetta 2 will go away, and Intel apps will die. (Just like 32-bit apps died in 2019.) When?

This is a boring question. You don't need to read this post. I'm only writing it because I've put together this chart at least twice. Maybe three times. Next time I wonder, I'll just re-read this post.

TLDR: The answer is probably 2028 or 2029.

The common rag is that Apple doesn't do backwards compatibility, but that's wrong. They do backwards compatibility. They just consider it a time-limited phenomenon. They're surprisingly consistent about it.

Here's what I mean. I was most active in iOS development in the early years -- iOS 3 to 10-ish. That's when iOS was changing most rapidly. (Particularly the big UI redesign of iOS 7.) It was notable that Apple kept old apps working, with the old UI, when you upgraded iOS on a device.

Once you recompiled the app (with the latest Xcode), you were in the new world. That was the time to redesign your app UI to match the new OS.

Yes, that was extra work for developers. But I'm making a point: Apple put in a lot of work to ensure that OS upgrades didn't break apps for users. Not even visually. (It goes without saying that Apple considers visual design part of an app's functionality.) The toolkit continued to support old APIs, and it also secretly retained the old UI style for every widget.

But, as I said, this was a time-limited thing. After a few years, Apple started to drop the old UI style from the toolkit. Old apps got weird mis-sized buttons and so on. I particularly noticed this with My Secret Hideout, which I never recompiled beyond iOS 5. When iOS 10 came around, Apple started to drop old apps from the store (including Hideout) because they looked like ass. You can debate whether booting them was a good policy, but my app did look like ass. I hadn't touched the code in five or six years.

Five years is, as it turns out, Apple's unspoken time limit.

Here's Apple's first architecture transition:

• Last 68k Mac discontinued: 1996 (PowerBook 190, Performa 630)
• OS support for 68k Macs discontinued: 1998 (MacOS 8.5)

In other words, you might have bought a 68040 PowerBook in 1996. It got two years of OS support; then it was orphaned in 1998. That's way under the five-year limit I mentioned. Early days.

(EDIT: I originally wrote "discontinued in 1999", but it turns out it was 1998.)

On the other hand, the software support lasted longer:

• First PPC Macs: 1994
• 68k emulator discontinued: 2001 (MacOS X 10.0)

Developers started building apps with PPC support in 1994. (Those were the CodeWarrior years.) But non-updated 68k apps were supported via an emulator. That was retained through the Classic MacOS era; it was dropped when OSX hit. So seven years of backwards support.

(EDIT: I am corrected; the "Classic environment" kept supporting 68k Classic apps through MacOS 10.4 "Tiger", at least for PPC hardware. So more like twelve years.)

Moving on to Intel, the window is exactly five years:

• Last PPC Mac discontinued: 2006 (Power Mac G5)
• Xcode support for building PPC apps discontinued: 2011 (Xcode 4)
• Rosetta discontinued: 2011 (MacOS 10.7 "Lion")

What about the 32-bit software cutoff? That's the one everybody screamed about (in 2019). It's a bit difficult to nail down how long the transition was, though. 32-bit Mac hardware was only sold for a couple of years: 2005-2007, the "Core Solo" and "Core Duo" processors. After 2007, all Macs sold had 64-bit CPUs. Thus:

• Xcode support for building 64-bit Mac software added: 2006 (Xcode 2.4)
• Last 32-bit Mac discontinued: 2007 (2006 Mac Mini)
• Xcode support for building 32-bit Mac software discontinued: 2018 (Xcode 10)
• 32-bit Mac software support discontinued: 2019 (MacOS 10.15 "Catalina")

Twelve years! That's longer than Microsoft supported Windows 7.

Looking at it, I'm surprised that there still was 32-bit-only software out there. I don't mean "software left over from 2006"; obviously there was some but you knew it was ancient. I mean developers who had just kept on building 32-bit versions of their apps -- never shifting to "fat" (32/64) builds.

You can get into a deep well of reasons why adding 64-bit support was hard. Most of them boil down to dependencies: old libraries, frameworks, game engines. (I'm not even getting into the Carbon-Cocoa business.) I guess the real question is why this transition was slower than the PPC-to-Intel transition, which was nailed down in five years.

Some of that was Apple's own transition, which itself took a few years. The MacOS kernel jumped from 32-bit to 64-bit around 2010. Then there was the Finder, iTunes, and other Mac first-party apps. If Apple is behind, they can't really put pressure on third-party developers.

I suppose there was a lot written on the subject circa 2012 or so. I don't recall any specific articles, though, so I'll let it go.

I'm not providing much support for my "exactly five years" claim, am I? Sorry! It's easier to see in the year-to-year OS updates.

• I buy a 21-inch iMac (Intel Core i5): 2011
  • MacOS 10.13 "High Sierra" is the last OS that supports it: 2017
• I buy a first-gen iPad Pro: 2015
  • iPadOS 16 is the last OS that supports it: 2022
• I buy a 13-inch MacBook Pro (Intel Core i5): 2016
  • MacOS 12 "Monterey" is the last OS that supports it: 2021

I'm cherry-picking devices that I owned, because I kept a list. But the general pattern is consistent: five to seven years.

I don't think Apple is arbitrarily applying a five-year cutoff. (If they did, it would be exactly five years!) I feel like there's generally a hardware requirement, whether that's RAM or a GPU feature or some other motherboard element. But since Apple doesn't advertise hardware details, you have to dig into third-party sites to draw a complete chart. I'm not doing that.

The point is: Apple does the compatibility work for a five-year horizon. Maybe that winds up covering a six- or seven-year-old model; if so, great. If not, oh well.

Thus we can return to the original question:

• Last Intel Mac discontinued: 2023 (2018 Mac Mini, Mac Pro)
• Rosetta 2 discontinued: probably 2028 or 2029

They'll announce the deprecation at a WWDC in May (2028 or '29), then ship the de-Rosetta'd MacOS in the fall. Don't wait for the news, of course. Get your ARM builds in gear right now if you haven't.

Footnote: Obviously this post assumes "business as usual" over the next five years, which is, you know, a hell of an assumption. If Apple stops making computers in three months because there are no more CPUs, forget this whole post.