Download classic Mac OS in a browser window with Project Infinite Mac.

For retro computing enthusiasts, there is no substitute for digging up ancient hardware and computing like it’s 1999. But just like with old video games, emulation offers a much more convenient way to run old software. Now, running System 7 or Mac OS 8 on a virtual Mac 68k is more convenient than ever thanks to a clever project called “Infinite Mac”.

What makes a project unique isn’t necessarily that it’s browser-based; It has long been possible to run older versions of DOS, Windows, and Mac OS in browser windows. Instead, developer Mihai Parparita has come up with creative solutions for persistent storage, fast download speeds, reduced CPU usage, and file transfers between a classic Mac and whatever host system you use it on. Parparita details some of her work in this blog post.

Starting with a browser port of the Basilisk II emulator in late 2017, Parparita wanted to install older apps to more closely recreate the experience of using an old Mac, but he wanted to do so without the need for large downloads or running as a standalone app. program, as the Macintosh.js project does . To solve the boot issue, Parparita compressed the disk image and split it into 256KB chunks that are downloaded on demand rather than preloaded.

“Along with some old-fashioned web optimizations, this allows the emulator to render the Mac boot screen in a second and fully load in 3 seconds, even with a cold HTTP cache,” wrote Parparita.

CPU usage was another issue. Older operating systems and processors did not distinguish between active and inactive states of the processor – your computer was either on or off. So when you emulate those older systems, they push one of your CPU cores up to 100%, whether you’re actually using the emulator or not. Parparita used the Basilisk II’s existing features to reduce CPU usage by requiring full performance only when “there was user input or a screen refresh needed”.

Infinite Mac will not work with later releases of the classic Mac OS (including 8.5, 8.6, and 9) because those releases ran exclusively on PowerPC Macs and support for older Motorola 68000-based processors was dropped. Emulators like QEMU can emulate PowerPC Macs, but (at least to my knowledge) there are no simple browser-based implementations. Anyway, not yet.

Listing image from Infinite Mac