Arm-Intel-PowerPC Universal Binaries Are Possible
Casual MacRumors visitors may not realize that we have a very active PowerPC forum where users discuss issues related to PowerPC Macs that have not been produced since 2006. Threads range from hardware upgrades and software options to nostalgia:
In particular, MacRumors forum member Wowfunhappy asked about ongoing support for Universal binaries in the upcoming Arm-based macOS, and whether or not a four-way universal binary was possible:
During their 2020 WWDC keynote, Apple announced the reintroduction of Universal Binaries, for developers to create apps that work on both Intel and Arm Macs during the transition.
But Universal Binaries never really went away the first time! You can run PPC-Intel apps on Mojave, and I assume also Catalina. Also, many Intel-only apps are still "universal," in that they contain versions for both i386 (32bit Intel) and x86_64 (64bit Intel).
Thus, I am intensely curious: would it be possible for a developer to create a single universal binary that works natively on all four architectures: PPC, i386, x86_64, and ARM?
The answer, it appears, is yes. The TenFourFox developer blogged about the possibility, confirming that it is indeed possible:
A question I got repeatedly the last couple days was, now that AARM (Apple ARM) is a thing, is the ultimate ARM-Intel-PowerPC Universal Binary possible? You bet it is! In fact, Apple already documents that you could have a five-way binary, i.e., ARM64, 32-bit PowerPC, 64-bit PowerPC, i386 and x86_64. Just build them separately and lipo them together
TenFourFox is a Firefox port for PowerPC Macs running OS X 10.4 or 10.5. It provides those users with modern browser support. The developer actually points out that each architecture can even have its own subtype, meaning that ultimately a so-called "Super Duper Universal Binary" could have support for 17 different instruction sets, which could run on any machine from PowerPC to future Arm-based Mac with full support for all processor subtypes.