In August 2006, I posted instructions on how to install Windows XP onto an external USB drive to the macrumors.com forums. I’m reposting the instructions here so that this information does not get lost.
Some notes on these instructions:
- These instructions result in an installation of Windows XP that is completely contained on an external USB drive. Other approaches usually create a Windows partition on the internal drive.
- The instructions require you to remove your internal drive from your MacBook during the installation. If you do not remove the internal drive you risk damaging the operating systems installed on your internal drive. Also, if the internal drive is not removed then Windows will not correctly install onto the external drive.
- For the past year I have relied on VMware to eliminate the need to boot to Windows on bare hardware.
Windows XP on USB for MacBook instructions:
Steps:
- Modify Windows install CD to support booting off a USB drive. (Instructions are on the web. Original page no-longer exists. A snapshot is held at the wayback machine. I also have a PDF file.)
- Remove internal hard drive from MacBook.
- Connect external USB drive to MacBook.
- Boot from modified Windows install CD.
- Progress through Windows install, creating partitions and formating the partitions as you see fit. In most of my installed I partitioned the drive under OS X using a firewire connection to the drive since Disk Tool isn’t always happy partitioning USB drives. I have also successfully used a GParted boot disk to partition an external USB drive and then running the Windows installer without modifying the partition table on the external drive.
- Wait for about 34 minutes for the Windows install to finish.
- Reboot into Windows on the external drive.
- Install the Apple device drivers for windows.
- Replace internal drive.
After all of this you will be able to boot into OS X. You will not be able to boot into Windows by holding down the option key when booting. Instead you will need to connect the USB drive to a running OS X system, open the Startup Disk Preference Pane and select the windows partition. Then when you reboot you will boot into Windows. To return to OS X you need to use the Windows Startup Disk control panel to select OS X.
(OS X will also boot if the USB drive is not connected.)
This fiddling with the Startup Disk Preference Pane is a limitation that I haven’t found a way to work around. For me, I can live with this since I only boot to Windows occasionally.
Additional notes:
- I have always plugged my USB drive into the rear-most USB port on my MacBook (the USB port closest to the MagSafe power connector). Some forum posts report that using another USB port results in Windows errors.
- Windows is unable to use a pagefile that on an external USB drive. After completing a install based on these instructions you will not be able to set up a working pagefile for Windows. Since I rarely boot to Windows and only then put it to light use then my 2GB of main memory means that I don’t require a working pagefile. Realistically, if you have less than 1.5GB of RAM in your Mac then you are will have problems with Windows running out of memory. Your mileage may vary.
- Even after following these instructions exactly some people have reported that they are unable to successfully boot Windows. It is likely that these failed attempts are due to differences in USB enclosure implementations and/or Windows memory issues.