At WWDC 2006, Steve Jobs said the following about porting OS X to the Intel architecture
“Porting an operating system to an entirely different processer architecture is no easy task and our software team did a magnificent job of taking this on the PowerPC and turning it into this on Intel architecture. So they made it look really easy and it’s gone seamlessly which has enabled this amazing transition to occur in 210 days, but under the hood and you all know, this was 86,000,000 lines of source code that was ported to run on an entirely different architecture with zero hiccups.”
But has the transition really gone that well? I suppose at the time it had, but almost six years on what can be said? Let’s take a quick look at the history of OS X on Intel.
At WWDC 2005 Jobs told us that each release of OS X had been compiled for the Intel architecture, he even had an iMac running Tiger on an Intel Pentium 4.
Tiger became publicly available for Intel Macs in January 2006 with the release of the MacBook Pro and the first Intel iMacs.
Tiger on the PowerPC (PPC) supported the Classic environment, which ran apps designed for OS 9 and also included the Motorola 68K emulator. So Tiger on PPC supported apps which were ages old.
On Intel, Tiger supported Rosetta, a translator allowing PPC apps to run on Intel Macs.
Tiger supported PPC Macs from the G3 to the G5, machines that were around 7 years old as of 2006.
Leopard supported G4 and G5 Macs (above 867MHz) and Intel Macs. Leopard lost support for the Classic environment on PPC apps, losing support for a plethora of apps created over a number of years.
Snow Leopard stopped support for the PowerPC but still had Rosetta built in, most PPC apps still worked, though a few had some oddities.
In 2011 Apple released Lion. Lion dropped support for 32-bit Intel Macs and no longer included Rosetta. All of the PPC apps that hadn’t been ported to Intel were lost.
Any app whose developer has abandoned it on some download site may well never run again…
So, while I am sitting here now on my 2011 iMac running the latest developer build of Mountain Lion, I can say that I am still running OS X. Many of the OS X features still exist. Apps classically available to OS X can also be run. But what about other apps, such as Adobe Freehand, have been left in the cold, not being able to be run on modern Macs.
Apple have been ruthless in the past; stripping away the original Mac OS codebase for one based on NeXTSTEP, swapping the floppy drive for a CD/DVD writer, getting rid of the optical drive altogether. But all through these changes they have kept the ability to run old software, tools that people use everyday. With the transition to Intel, Apple threw away so much, and what they kept seems to have been too much to maintain.
Out with the old and in with the new. It doesn’t really affect me, I occasionally come across a PowerPC only app, but nothing show stopping. It does go to show how ruthless Apple can be, with everything, even software.
Bootnote: This is an old post that I’ve tidied up a bit, the thread was somewhat lost in the time between when I first thought of it and now.