By Jason Snell

March 24, 2021 4:31 PM PT

From Classic to Cocoa, via Carbon

If I close my eyes, I can picture the classic Mac OS laid out before me. I can imagine every menu, every mouse gesture, the sound of the Mac SE chime, even depressing the reset switch after a hard crash.

The thing is, I didn’t become a Mac user until early 1990. I had used two other computers before I found the Mac. I can’t remember anything about the Commodore PET other than the READY. prompt. The Apple IIe made a bigger impression, but in retrieving all my old disks from that period, I discovered that I remember almost nothing beyond how to control a few of my favorite games.

I’m not sure quite why the classic Mac is so indelible, though some of it has to be its consistency. In the early days of the personal computer, you either had no user interface, or every user interface was different. My Commodore PET was an all-text experience. The Apple IIe was much more interesting, but commands and controls varied from program to program. The Mac’s personality was present and consistent, even as I swapped disks or switched between apps.

Given the arrival of Mac OS X 20 years ago, I really only spent about 11 years with the classic Mac OS. Yet it still sticks with me, not only because that period coincides with college, grad school, first jobs, getting married, and starting a family. (My daughter also turns 20 later this year.) But also because the classic Mac OS inspired Mac OS X, providing a continuity that means a Mac user from the mid-1980s dropped in front of a Mac today would be able to at least recognize a few things.

This was not a foregone conclusion. Having utterly failed in its own attempts to create a new, modern version of Mac OS, Apple bought NeXT and imported the NeXT software team to build a new operating system on top of the NextStep foundation. Apple was much bigger than NeXT, but the people from NeXT had the home-field advantage with their software. And there was the even bigger advantage that, after a few months, their old boss Steve Jobs was in charge. Given how deeply unimpressed Jobs had been with the state of Apple when he returned, it’s not unreasonable to imagine that Jobs would favor NeXT tendencies over Apple ones when it came to building the new Mac OS.

And the thing is, they sort of tried. Early attempts at Mac OS X—Rhapsody, Mac OS X Server, and even some of the developer betas—were far more NeXT-flavored than the final version. But perhaps biggest moment came when Apple and Jobs tried to import NeXT’s software development approach to the Mac.

Put simply, NeXT had its own way of writing apps. And originally, that was going to be the favored way of getting apps on the new version of Mac OS. This approach ultimately did pay off—not only did it import a bunch of NextStep developers like The Omni Group to the Mac, but it was the basis of Cocoa, the basis of all modern Mac apps and the foundation of iOS apps as well.

But at the time, Mac developers weren’t having it. Microsoft and Adobe, especially, were not interesting in writing new versions of Office and Photoshop for the new Mac platform. Even though they were inclined to stick with the Mac (which was only beginning to bounce back thanks to the iMac and a bunch of other interesting new Mac hardware), rewriting was out of the question. And running their apps in a weird Mac compatibility window—another initial proposal—wasn’t going to cut it.

Apple went back to the drawing board. And the version of Mac OS X that shipped as version 10.0 twenty years ago supported both NextStep-style apps, unmodified Mac apps (via a weird virtual-machine layer called Classic), and apps written using something called Carbon. Carbon, which was a modernized and simplified version of classic Mac OS technologies, was vital to the success of Mac OS X. Microsoft, Adobe, and countless other developers were able to bring their classic Mac apps over to OS X via Carbon—not without effort, but with a reasonable effort.

And so as 2001 became 2002, as 10.0 became 10.1 and was on its way to 10.2, Mac OS X ended up playing a lot of familiar notes for Mac users. It looked a lot like Mac OS, glammed up with the Aqua interface and with this weird new thing called the Dock (a NextStep touch that made it across), and it ran Mac software. Not just in Classic, either, but natively as an increasingly large number of popular Mac apps were upgraded.

Over the years, Apple deprecated Carbon, and the last vestiges of it really died when macOS Catalina killed off 32-bit apps in 2019. But it did its job. Not only was Mac OS X modern and ready for the future in a way the classic Mac OS wasn’t, but it felt familiar enough, both in terms of its design and in the software that it ran, for Mac users to embrace it.

I can’t say enough about how important Mac OS X was to Apple. By buying NeXT, Apple not only brought Steve Jobs into the fold, it brought the technology that would serve as the basis for OS X, iOS, iPadOS, tvOS, and watchOS. NeXT’s approach is at the heart of every iPhone and iPad app.

We’ve come a long way in 20 years, to be sure. And it feels like this decade will change the Mac in ways that it hasn’t changed since those early days of OS X. But my Mac still feels like the Mac. And when I close my eyes and imagine my Mac SE in 1990, I feel the familiarity and continuity that extend through Apple’s products to this day.

[OS X 10.0 images courtesy of Stephen Hackett.]