Boot the classic Mac OS into your browser window with the “Infinite Mac” project

The Infinite Mac project that emulates a classic System 7 Mac.
enlarge The Infinite Mac project that emulates a classic System 7 Mac.

For retro computer enthusiasts, there is no substitute for digging up old hardware and computers like it was in 1999. But as with old video games, emulation provides a much more convenient way to run old software. Running System 7 or Mac OS 8 on a virtual 68k Mac is now more convenient than ever, thanks to a clever project called “Infinite Mac”.

What makes the project unique isn’t necessarily the fact that it’s browser-based; it has been possible to run old DOS, Windows and Mac OS versions in browser windows for quite some time now. Instead, it’s the creative solutions that 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 using it on. Parparita describes some of his work in this blog post.

Starting with a late 2017 browser-based port of the Basilisk II emulator, Parparita wanted to install old apps to more faithfully mimic the experience of using an old Mac, but wanted to do this without massive downloads or running as a separate program as the macintosh.js project does. To solve the download problem, Parparita has compressed the disk image and divided it into 256K chunks that are downloaded on demand rather than pre-load.

“Along with some good old-fashioned web optimizations, this makes the emulator show the Mac startup screen in a second and boot completely 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 on or off. So when you emulate these 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, requiring full performance only when “there was user input or a screen refresh was required.”

Infinite Mac will not run later releases of the classic Mac OS (including 8.5, 8.6, and 9) because those releases ran exclusively on PowerPC Macs, eliminating support for the old Motorola 68000-based processors. Emulators like QEMU can emulate PowerPC Macs, but (at least as far as I know) there are no easy browser-based implementations. Not yet anyway.

List image by Infinite Mac

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