For retro computer enthusiasts, there’s no substitute for discovering old hardware and computing like it was in 1999. But as with older 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; it’s been possible to run older versions of DOS, Windows, and Mac OS in browser windows for quite some time now. Instead, it is the creative solutions that Developer Mihai Parparita developed to enable persistent storage, fast download speeds, lower CPU usage, and file transfers between the classic Mac and the host system you’re running it on. Parparita details some of her work in this blog post.

Starting with a port of the browser-based Basilisk II emulator in late 2017, Parparita wanted to install older apps to more faithfully recreate the experience of using an older Mac, but wanted to do so without requiring huge downloads nor run separately. program like the Macintosh.js project does. To fix the download issue, Parparita compressed the disk image and split it into 256KB chunks that are downloaded on demand rather than in advance.

“With some old-school web optimizations, this allows the emulator to show the Mac splash screen in a second and be fully booted in 3 seconds, even with a cold HTTP cache,” Parparita wrote. .

CPU usage was another issue. Older operating systems and processors didn’t really distinguish between active and idle processor states – your computer was either on or off. So when you emulate these older systems, they cause one of your CPU cores to go to 100% whether or not you’re using the emulator. Parparita used existing Basilisk II features to reduce CPU usage, only requiring peak performance when “there was user input or a screen refresh was needed”.

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

Listing image by Infinite Mac