For retro computing enthusiasts, there’s no substitute for digging up old hardware and computing like it’s 1999. But like old video games, emulation offers a much more convenient way to run old software. Now running System 7 or Mac OS 8 on a 68k virtual Mac is more convenient than ever, thanks to a clever project called Infinite Mac.
What makes the project unique isn’t necessarily that it’s browser-based; old versions of DOS, Windows and Mac OS have been able to run in browser windows for quite some time. Instead, it’s the creative solutions Developer Mihai Parparita designed to enable persistent storage, fast download speeds, reduced processor usage, and file transfers between the classic Mac and the host system you’re running it on. Parparita describes some of his work in this blog post.
Starting with a browser-based port of the Basilisk II emulator in late 2017, Parparita wanted to install old apps to more faithfully recreate the experience of using an old Mac, but he wanted to do so without requiring large downloads or running a separate program like the Macintosh.js -Project. To solve the download problem, Parparita compressed the disk image and split it into 256K chunks that are downloaded on-demand rather than in advance.
“Along with some old-fashioned web optimizations, this gets the emulator to the Mac’s home screen in a second, and fully boots up in 3 seconds even with a cold HTTP cache,” Parparita wrote.
CPU usage was another issue. Old operating systems and processors didn’t really distinguish between active and inactive processor states – your computer was either on or off. So when you emulate those old systems, they will boost one of your CPU cores to 100% whether you actually use the emulator or not. Parparita used existing Basilisk II features to reduce CPU usage, only requiring full performance when “user input was being provided or a screen refresh was required”.
Infinite Mac will not run later versions of the classic Mac OS (including 8.5, 8.6, and 9) because those versions ran exclusively on PowerPC Macs and support for the old Motorola 68000-based processors was dropped. Emulators like QEMU can emulate PowerPC Macs, but (at least as far as I know) there are no simple browser-based implementations. At least not yet.
Promotional image of Infinite Mac