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Intel Mac Chip Story
by Jason Snell

We used to have G3, then G4, then G5. So what's inside these new systems a G6?
G5 is the last G we'll see. The chip powering the new iMac and MacBook Pro systems is Intel's brand-new Core Duo processor. It's a chip designed to be both powerful and energy-efficient, and it was designed by Intel for use in laptops although clearly it's also appropriate for use in ultra-thin desktops like the iMac.

Like the G5 chips in the last round of Power Macs, the Core Duo is what's called
a dual-core chip. That means that there are essentially two processor brains on the Core Duo chip, providing the speed of two processors, but with lots of energy efficiencies. It's also got 2MB of level 2 cache, which is speedy RAM that's attached directly to both processor cores-that's four times more cache than on previous Power Macs and iMacs. (And since one single cache is shared by both processor cores rather than split into two, it's even more efficient.)

The end result of all this is that although the Core Duo chips in the iMac and MacBook Pro are similar in clock speed to their G4 and G5 counterparts, the systems are much faster because the chips have two processor cores instead of one and a lot more cache RAM.



Wait a second what about the "megahertz myth?" I thought when we went to Intel, we were going to get blazing-fast chips!
A funny thing happened on the way to 3GHz, and it happened to both IBM and Intel. Intel, which had succeeded at driving chip clock speeds higher and higher and convincing customers that clock speed equated to actual processor performance, hit a clock-speed wall. To hear Apple engineers tell it, Intel realized that it needed to make a 90-degree turn, go through a seriously painful transition period, and revamp its processor roadmap to emphasize more efficient chips that could do more at lower clock speeds.

That was a decision that fed directly into Apple's decision to make the move to Intel. With the latest generation of Intel chips, such as the Core Duo, Apple finally has a set of chips that provide the thermal- and power-management strengths of the G4 processor (vital for laptops and cozy iMac cases), but with speeds more in line with the power-hungry, super-hot G5 processor.

So how much work did Apple need to do to make OS X run on Intel?
Steve Jobs might have had a smile on his face when he told the story last June, but he wasn't kidding: ever since the beginning of Mac OS X, there was a group at Apple dedicated to compiling and running OS X on Intel processors.

From the very start, Apple wanted to keep its options open. And so when it came time to make the transition, the company didn't need to launch a grand project to make the transition. It just needed to bring this skunk-works project out into the light.

Now with the release of these new systems, there are two versions of Mac OS X 10.4 Tiger: one compiled for Intel and the other for PowerPC.


How is this different from the OS 9 transition?
It's pretty different. For most developers, modifying their software to run on Intel processors will be quite a bit easier than making that software run natively in OS X. From a user perspective, an Intel-based Mac system will look just like a PowerPC-based system. Mac OS X is remaining the same; it's just the underlying processor that will be different.

Does this affect the software I already own? What will happen to my software if I buy an Intel-based system?
The Intel version of Mac OS X features a technology called
Rosetta, which Apple describes as a dynamic code translator. Basically, Rosetta takes program code created to run on a PowerPC processor and translates that code into its Intel equivalents.

If you recall running 680x0 code (say, Microsoft Word 5.1) on a Power Mac back in the mid-90s, you know what this means: programs run slower when they're not running on their native processors.

Back in the day, we used to say that programs such as Word 5.1 were running in "680x0 emulation." Rosetta is a similar system, but Apple is trying very hard not to use the word emulation here, largely because most people think of programs such as Virtual PC when they hear that word. Rosetta isn't anything like Virtual PC or even Classic-in fact, from a user's perspective, there's no way to tell when you're using a program running in Rosetta or when you're running a Universal program-Apple's term for a program that runs natively on both PowerPC and Intel processors.

Last June, there was a lot of speculation that Rosetta would refuse to run certain kinds of programs. But according to Apple, that's not true-Rosetta will try to run anything you throw at it. However, programs that are extremely processor-intensive will probably not run at acceptable speeds. For example, Apple says that Final Cut Pro will run under Rosetta, but that it won't really be usable and that Apple itself won't support such attempts.

Will Classic mode run under Rosetta?
No, Classic mode won't run on Intel Macs at all. If you still rely on Classic applications, Intel-based Macs aren't going to work for you. This would probably be a good time to begin investigating OS X-native alternatives to the Classic programs you're currently using.

How can I tell if a program I've got is Universal or not?
The only real way you'll be able to tell what processors a program is compiled for will be to select a program in the Finder and choose Get Info. In the More Info selection of the Get Info window, you'll see an Architecture: line that will list Intel, PowerPC, or both. (There's also an "Open using Rosetta" checkbox that might be useful in certain oddball situations, much as "Open using Classic" is today.)
Better yet, check with developers of the programs you're interested in to see if they've got a Universal version in the works. They'll probably be happy to tell you.


Will I have to buy new versions of my software specifically to run on an Intel-based Mac?
As with the PowerPC and OS X transitions, there's no single answer. Different developers will handle things differently. One company might offer an Intel-compatible version as a free upgrade; another might build it into the next major release and charge you for the privilege.

In the past few months, many developers have released minor updates to their products that have also transformed them into Universal programs; Bare Bones Software's BBEdit and TLA Systems' DragThing both fall in this category. Apple itself has said that Final Cut Studio, Logic Pro, and Aperture will all be available in Universal form in March for a $45 "cross-grade" fee. It's possible that programs from large developers-Microsoft Office and Adobe Photoshop, for example-won't be Universal until the next full version of those products is released.

Because of Apple's new "Universal Binary" approach, developers can deliver a single program that contains within it both Intel and PowerPC versions of their software. You won't have Intel apps and PowerPC apps floating around, making it easy to click on the wrong one (and making it impossible to drag-and-drop software from an Intel Mac to a PowerPC one). And future Mac software will likely be sold simply as Mac software, not specifying whether it's Mac for Intel or Mac for PowerPC - you'll install it, double-click on the program, and your computer will use the right code for its processor.

Now that the first new Intel Macs have come out, should I go buy one?
It's possible that these new, first-generation Intel systems will not be without their quirks. If you rely primarily on programs that currently don't exist in Intel versions, you may not see any of the speed benefits Apple advertises. If the programs you use all the time are already Universal-for example, iLife, Safari, Mail, iChat, stuff like that-then you will be much more likely to reap the speed benefits of these new Macs.


Can these Intel-based Macs run Windows?
Ask people from Apple this question, and they'll do one of two things: shrug, or plug their ears and pretend they can't hear you. Basically, Apple's official policy is that if someone wants to figure out how to run Windows on a Mac, they can go ahead and do it, but Apple doesn't want to know about it.

One interesting quirk of these new Intel-based Macs is that, unlike the developer test systems released last summer, these systems use Intel's Extensible Firmware Interface (EFI) instead of the tried-and-true BIOS that classic PCs use. Windows XP doesn't actually support EFI, although the forthcoming Windows Vista will.

So the question is, how will people get Windows to run on the Mac? We're sure someone much smarter than us will figure it out. Whether you'll be able to re-boot into Windows or run it in some sort of compatibility box-hello, Virtual PC!-remains to be seen.

Contact Miss Mac for Troubleshooting, Maintenance or Tutoring: Whether you choose to be a do-it-yourselfer or not, you should periodically subject your system to evaluation, maintenance, tune-up or needed tech repairs, unless of course you are practically a Mac tech yourself.

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