Where are the PPC Emulators?

mikenetaim asks: "Numerous people have started projects aimed at emulating the PPC based Macintosh. Those that run on machines with a PPC tend to succeed (MacOnLinux, Sheepshaver, iFusion), and every single one which attempted to emulate the CPU failed. Everyone admits that an emulated CPU will run slowly, but no one has ever released a working PPC emulator at any speed (except for an incomplete one, whose name escapes me, that was released a long time ago to statically translate AIX binaries). There are a ton of 68k emulation code floating around the 'net, and a PPC emulator should be easier to produce (due to fixed instruction length, branch predication, opcodes that dictate if CCR flags must be generated, etc). Most of the authors just claim their project was harder than they expected before disappearing. Why do all these projects fail? Can anyone point me to any information or code?"

Comments

Jimmy Drew:

[Chasing Amy]

You're absolutely right that Jim Drew's reputation in the emulation community is crap. He always delivers what he promises years late and with big features which were advertised early on in the project lacking.

In the case of his PPC emulation, it's over a year late already, and he announced around December that it would show at MacWorld Tokyo. Given his typical timetable for falling behind, even if it's not finished yet, it should be finished for sure and on the market (if the hardware company lets it be) before the year is out.

That said, there's no telling whether the iMac emulation will be complete. I'm betting that it will initially only support OS 9 due to incomplete implementation--but that eventually, it should be able to run OS X with some finegling, especially since the Darwin layer is open-source and people have already hacked it to make OS X run on unsupported machines with processor upgrades.

No, Jim Drew isn't timely and he's liable to hype. And in fact, most of the emulation scene hates him right now for letting everyone believe up until the last minute that his PPC emulator would be demoed at Macworld Tokyo. But he does *eventually* deliver products that offer good Mac emulation. Fusion was, for example, the best 68k Mac emulator by far when it first came out, and then for some time afterwards, although Basilisk II slowly but surely beat the crap out of both Fusion and its competitor SoftMac.

At any rate, I think hadware-assisted is the way to rally go for PPC Mac "emulation" on the PC. There are so many high-quality PPC add-in cards out there now, that people really interested in running PPC code on their machines should pick one that's available in decent quantities and start coding the emulation support for it. After that, once the core "glue" emulation is done that can emulate the other Mac hardware and hand off instructions to the PPC add-in card, other PPC add-in boards could be supported, and Darwin could be hacked where necessary to allow OS X to work with any shortcusts that might need to be taken, much as it is hacked now to get OS X working on unsupported Macs with upgrade cards.

It's very doable when approached that way; unfortunately, no one but Drew seems to have been interested in that path. It's a pity, because even though it's more of an accomplishment to emulate a PPC CPU, it's much more practical and could be done much faster if one just emulates the other hardware on a given PPC Mac and "glues" it into using the PPC card for processing. Plus, it would allow the PPC Mac OS to run simultaneously with a Linux or Windows that's actually usable, whereas a "pure" emulation would eat up *all* the x86 CPU's cycles and make it so that one could only practically use the Mac emulator and nothing else.

Wouldn't it be great to have a fully working PPC processor card running Mac OS X, while simultaneously being able to use x86 Linux or Windows on your x86 CPU, all on the same machine? *That* is the idea we should really be going for, not a totally-emulated PPC core. PCI G3 and G4 Mac upgrade cards are *so* plentiful--why aren't more people trying to put them to use for Mac emulation on the PC?