Click the Erase button in the Disk Utility toolbar.

Do not select the volume located just underneath the device name. The device will likely have the name of the external enclosure’s manufacturer listed.

In the Disk Utility sidebar, select the external drive that will be used for Windows.

Launch Disk Utility, located at /Applications/Utilities.

Ensure the external drive is connected to your Mac.

Warning : The erase, format, and partitioning process will delete all data currently contained on the external drive. The external drive that you’ll install Windows on needs to be prepared by erasing and formatting the drive for use with Windows.

Prepare the External Drive for Installing Windows If you’re not using a portable Mac with a built-in keyboard and trackpad, you’ll need a wired keyboard and mouse to complete the installation. During the Windows installation, the drivers for Apple wireless keyboards and mice aren’t installed until the very end of the process.

A licensed copy of Windows 10 ISO or an install DVD.

VirtualBox virtualization app (available for free).

We’re using a USB 3.0 drive, but a Thunderbolt drive should work as well.

What You Need to Install Boot Camp on an External Drive Also, make sure you have a current backup before beginning. Be sure to read through the process before undertaking it. This is an advanced process with quite a few pitfalls that can trip you up. It allows you to install Windows on an external drive without first having Windows installed on a PC or in a virtual environment. But the method we’re going to outline here is a bit different. They range from creating clones of an existing PC installation or using Microsoft IT tools for installing Windows. There are actually a few ways you can successfully install Windows on an external drive. Installing Windows on an external drive would be a great solution to the problem of available space, but as we said, Boot Camp and Windows impose a restriction on installing to an external drive. While Boot Camp Assistant can partition your startup drive for you to make room for Windows, there are bound to be many of you who just don’t have room to spare on your startup drive to install Windows. One of the downsides to Boot Camp and the Windows installer is that it restricts you to only installing Windows on your Mac’s internal drive. It’s a nice capability that lets you select – at boot time – which operating system you wish to use: macOS or Windows. Boot Camp and Boot Camp Assistant allow you to install Windows on your Mac.

Mac windows xp emulator 10.11.6