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Will Intel Macs run Windows? - Part 1
The answer is No. And Yes. And It Doesn't Really Matter. Read on to find why.

Part 1: No - Why the new Macs can't run Windows, page 2.

Additional hardware

There are more hurdles to booting Windows beyond the Mac EFI firmware. Even if you could boot Windows, the new Macs use hardware that is not supported in Windows. The MacBook Pro's illuminated keyboard system, as well as both of the new Mac's the power management fan controls and the built-in FireWire iSight are all examples of features that would require custom drivers under Windows.

Who would provide and maintain these? Microsoft doesn't write custom drivers for manufacturers like Dell, Sony, and HP; they write their own.

What about Apple? While they at one time officially supported MkLinux as an alternative OS on Mac hardware (around 1996), it is unlikely they would devote the resources needed to make new Macs run flawlessly under Windows.

Apple does not currently provide direct hardware support for Linux, even though there is a significant minority of Linux users who now buy Powerbooks expressly to use with Linux. This is a real hardship for the open source community, as some hardware, notably the Broadcom wireless chipsets used in Airport Express, do not have published hardware stats that the community could use to write their own drivers.

That makes Apple's differentiating hardware features a second strike against realistically using Windows on a new Intel Mac.

Disk partitioning
A further problem for booting Windows on a new Mac is the disk partitioning. In addition to a disk format, such as the Mac's HFS Plus, or Windows' NTFS, computers use a partitioning table to define how each hard disk is set up. The partitioning table defines multiple volume partitions on a single drive. Even without multiple partitions, you still need a partition table, and Macs and PCs use different technology to manage this.

Macs currently use the Apple Partition Table to describe the partitions created on a drive. EFI uses a new format called GPT. This poses a minor problem for Mac users working between PowerPC and Intel Macs. Apple has simplified this transition both by enabling EFI Macs to work with exiting ATP drives, and by updating Mac OS X 10.4.4 to recognize the new GPT format on existing Macs.

There are still some rough edges; Apple currently recommends using APT for portable drives, and provides some warnings about using Intel Macs in Target Disk Mode with older Macs, and the Intel Mac OS X installer requires GPT in order to create a bootable volume.

On PC's however, the BIOS is tightly integrated with MBR (master boot record), which is the disk partition technology from IBM's first PC. Over the last two decades, MBR has been stretched to the limit, with hacks to support more than the four partitions it was designed to support, as well as disks larger than anyone could have ever imaged in 1982.

When a PC boots, BIOS drops control on code embedded in the MBR (on the disk) to determine which active partition to boot. Early viruses exploited this system to take control of a PC before the OS could even load.

All these issues are cleared up under Intel's new EFI firmware design, where the task of selecting the boot partition is given to EFI, not executable code on the hard drive.

As you may have gathered, Intel's EFI vision for the next generation of modern PC firmware looks a awful lot like existing Macs, where OpenFirmware selects and boots the user designated operating system from any available device. BIOS and MBR are really archaic garbage that have held PC users captive to inflexible booting options, and are wholly incompatible with the modern EFI and its GPT disk partitions.

All this technical talk on disk partitioning relates to the issue of running Windows on Macs because Windows has only ever needed to run on the old BIOS/MBR system. That means that even if you got past the firmware and driver issues, you'd still have headaches involved with getting Windows to recognize other drives, and it could not coexist on the same drive you use to boot Mac OS X. GPT and MBR can't both function on the same drive. Strike three!

There you have it: there's no question left about whether a Windows CD will install a dual boot Windows/Mac OS X installation on a new Dual Core Mac. Bummer! But wait, the answer in part two is "Yes!" ... so you might want to return to give it a read as well to see why.

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Will Intel Macs run Windows? Part 2


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