Rosetta: Compatibility with a Caveat
There’s yet another wrinkle in the performance of these new Intel-based iMacs: Different processors speak different languages. Programs compiled for the PowerPC chip can’t run natively on these new Intel CPUs. Instead, they have to run through Rosetta, an emulation technology that lets Intel-based Macs run PowerPC apps by translating their commands into ones Intel chips can understand.
All of our tests showed that PowerPC applications run less than half as fast on a 2GHz Intel iMac than on the 2.1GHz iMac G5. But those speed differences are relative. Yes, if you’re upgrading to an Intel-based iMac from an iMac G5 you bought just a few months ago, your PowerPC apps will run half as fast. But if you’re upgrading from a two- to four-year-old iMac, you might not see any slow-down—and you might see a speed-up.
For example, when we compared the new 2GHz iMac to a 700MHz iMac G4, the first-generation flat-panel iMac released in 2002, we found that the Intel iMac executed our Rosetta application tests much faster than its four-year-old predecessor.
Since many of the everyday applications people use aren’t particularly processor-intensive (Microsoft Office being a great example) those applications should probably seem quite usable under Rosetta. Other programs (games, for instance) may be well-nigh unusable.
The speed of applications running under Rosetta will be something to keep in mind, especially when it comes to the forthcoming release of the MacBook Pro. The users of that professional-level laptop are far more likely to demand serious speed from their applications; if there’s no Universal version of Photoshop available at the time, professional photographers may balk at the idea of running Photoshop at a fraction of its speed. However, given how relatively slow the current PowerBook G4 line may be, the situation may not be that bad. And since Photoshop can take advantage of the MacBook Pro’s dual-core processor, even a non-Intel version of Photoshop may be quite usable on the MacBook Pro compared to current PowerBook G4s. But we won’t know for sure until the MacBook Pro arrives and we have a chance to put it through the same tests as the Core Duo iMac.
iMac: Rosetta Application Tests
|iMac Core Duo 2GHz||iMac Core Duo 1.83GHz||iMac G5 2.1GHz||eMac 1.42 GHz G4||iMac 700MHz G4|
Best results in bold; reference systems in italic.
When Universal Isn’t Enough
But just because a program is Universal doesn’t mean that it’s reached its full speed potential on Intel-based Macs. Software development is an evolutionary process. Even if software vendors (including Apple) have delivered Universal versions of their apps in time to run on these first Intel iMacs, there’s every reason to believe they’ll continue to tweak and refine those apps to work better and better on the new CPUs. For example, Apple officials have admitted to us that iLife ‘06 could stand to be better optimized.
Those developers have already gone through that optimization process for PowerPC-based Macs. Some programs, for example, offer features written to specifically take advantage of the G4 and G5 processors’ Velocity Engine, a special set of accelerated commands. Many of these features will need to be modified to take advantage SSE/MMX, the Intel equivalent of Velocity Engine.
In addition, the tools that developers use—Apple’s Xcode development environment and Intel’s collection of code compilers—will also likely improve, making it easier for developers to wring even more performance out of their Intel-compatible software. Even portions of Mac OS X itself, although they do run natively on Intel processors, will likely benefit from further optimization.
Alien Software: Running Classic and Windows
The release of Intel-based Macs is a major milestone for users of Mac OS 9 software.
Intel-based Macs don’t support Mac OS X’s Classic mode. So if you rely on old-school Mac OS 9 applications to get your job done, these new Macs simply aren’t for you. While it’s extremely unlikely that Apple will ever bring back Classic, you may be able to use a Mac emulator, sort of like a Mac equivalent of VirtualPC. At press time, two emulators were already available in “experimental versions” for Intel Macs: SheepShaver, which emulates a Power Mac, and Basilisk II, which emulates either a Mac Classic or Mac II. But keep in mind that, since they’re both emulators, they’ll be running those Classic applications at low speed.
Anyone who’s had to keep a spare PC around the office to run Windows programs, on the other hand, might well have rejoiced at the news of Apple’s switch to Intel. But such rejoicing is, for now, premature. There isn’t yet a verified way to install Windows on your Mac and boot into it. (Intel-based Macs use a boot system called EFI, rather than the more traditional BIOS, which makes things harder: Windows XP doesn’t support EFI, although the forthcoming Windows Vista will.) But plenty of clever hackers working hard at the problem, and it’s only a matter of time before someone figures it out.
Still, it’s likely that Microsoft will also update Virtual PC so that it runs on Intel-based Macs. When that happens you can expect that it’ll run Windows at speeds approaching those you’d find on a normal PC. (It won’t be full-speed, however, because Windows will be running inside an application and sharing space with the rest of your Mac.) Other Windows-in-a-box products will probably appear as well. So the future of running Windows stuff on your PC will be bright, eventually.
Different Chips for Different Folks
The Intel Core Duo is a processor designed for laptops, providing a compromise between performance and good power-consumption and heat-generation characteristics. And so the Core Duo processor in these new iMacs (as well as the forthcoming MacBook Pro) is clearly not meant to be the be-all, end-all when it comes to raw computing power.
As a result, it’s difficult to take these first Intel-based Macs and try to extrapolate the entire future of the Mac product line from them. For example, Apple’s forthcoming professional desktop Macs—whatever they’re called, since they almost certainly won’t be called Power Macs—will most likely use a new, high-speed Intel chip designed specifically for desktop PCs. They’ll be fast, and they’ll be designed to trade off a bit in terms of power consumption in exchange for speed. (They’ll also probably support 64-bit processing, which is important to many users of the current Power Mac G5.)
On the other end of things, there’s no way of telling how Apple might take advantage of the forthcoming low-power version of the Core Duo processor, not to mention the Core Duo’s low-power single-core sibling, the Core Solo. All of Intel’s various chips give Apple a large palette to paint with; the big mystery is which colors Steve Jobs will choose to use.
The Last Word
With two iMac models as our only solid evidence of the Mac’s transition to Intel processors, it’s far to soon to issue any final judgments about how the transition will go. There are still lots of huge questions yet to be resolved, including the speed of the MacBook Pro, the speed of Apple’s forthcoming Universal versions of its professional applications, and just how fast the first professional Intel-based desktop Macs will be. (Even more tantalizing are the forthcoming Mac models we can’t even anticipate yet!)
However, these new iMacs do clear up several mysteries and generally make us feel that the Intel transition may be a pretty smooth one. Apple’s claim that the new iMac is 2x faster than the previous model may be debatable, but the fact that it is noticeably faster at almost every native task—and much, much faster at tasks that are multiprocessor-friendly—is indisputable.
We also expect that as time goes on, the apparent speed of these first Intel Macs will increase, thanks to optimizations in Mac OS X and individual applications that take better advantage of multiple processors and specific traits of the Intel-based Mac architecture. And of course, as programs that currently run in Rosetta are updated to be Universal, users will see notable speed improvements.
Most importantly—and when we get deep down into talking about chips and test results, it’s easy to fail to see the forest for the trees—these new systems are Macs, period. That Intel chip embedded deep inside may have a lot of meaning when it comes to the appearance, features, and performance of future Mac models—but you’d never know it from sitting down at one of these iMacs. The Intel revolution has begun, not with a bang, but with a familiar and comforting Mac boot-up chime.