Because the Classic environment was itself an app, all the programs that ran inside it were protected from interfering with other Mac OS X programs and vice versa. The Classic environment set up a sandbox that looked enough like Mac OS 9 to run Classic Mac OS programs directly in Mac OS X. But Apple didn’t want to just leave OS 9 programs behind, so they did two things: Mac OS X was a huge step forward from Mac OS 9 in a number of ways, including preemptive multitasking so that you could actually run multiple things at once. Its successor Mac OS X 5 also ran on PowerPC when it first launched it wasn’t until 10.4 that Apple began to switch to Intel processors instead, and 10.6 when PowerPC was finally dropped. Mac OS 9 ran on PowerPC processors, which were also used in the GameCube, PS3, and Xbox 360 earlier versions of the OS had started on Motorola’s 68k CPU series. 4 If a program crashed or overwrote memory it wasn’t supposed to, there was a good chance you’d have to restart the whole system. It also dates from the days when only one program could run at a time because of that, even the latest version uses cooperative multitasking to run multiple programs-that is, a program has to yield its time to let others run. 3 It was one of the first OSs to use a GUI at all, something that we pretty much take for granted these days. Twenty (!) years ago, before the macOS 2 we know today, there was another operating system known as “Mac OS”. This year I decided to seriously attempt something that I’d thought about in the past: getting a Swift program to run on Mac OS 9. Last year I implemented the world’s best code visualizer. And while pranks on April Fools’ seem less and less fun 1, obvious jokes and whimsy, not at anyone’s expense, are still something I believe in…and even better if they actually work.

While this year is a sober one due to current events, I think a lot of people still appreciate what people are creating and sharing to keep spirits up, whether that be music or art or…impractical programming projects. It’s April 1, and that means it’s both April Fools’ Day and the anniversary of the founding of Apple Inc.

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