Using Bootcamp is it possible to run OS X and Windows simultaneously such that I can command-tab between the two? I've run Windows using Bootcamp a few years ago but at that time a restart was required when switching between OS X and Windows.


Bootcamp is designed to allow you to change your operating system while the computer boots.

Nothing allows you to swap purely back and forth between operating systems that way. What you can do is use software that runs Windows in OS X with hardware virtualization, a huge step up from the software virtual machines of old.

There are three good options: Parallels, VMWare Fusion, and VirtualBox, the last of which has the advantage of being free.

If you want more technical details, particularly the ones that drove an edit to improve this answer, read the comments below.

  • +1 ironically, I totally forgot about VirtualBox, even though that's the one I use. May 28 '11 at 2:13
  • ....Uh... Virtualbox uses the same virtualization techniques as Parallels and VMWare Fusion. I don't know where you got the Idea it didn't. It does let you turn them off, if you want, but they are normally enabled. The major speed differences come down to different drivers for the virtual hardware used to interface with the VM.
    – Fake Name
    May 28 '11 at 8:53
  • @Fake Hmm, someone whose low-level OS knowledge I trust explained to me at some length a couple of weeks ago how they were different. Let me do a bit of research and I'll come back and change my answer if I don't have something solid to point to. Thanks for bringing it up, and no need to start with "....Uh" and such: SO/SA is a fine place to correct someone with facts, I certainly don't mind being wrong now and then. Let's just keep it about supplying the best answers. May 28 '11 at 9:01
  • All three virtualization systems listen leverage hardware virtualization extensions (AMD-V/VT-x if you have them), and none of the above use hypervisors.
    – Fake Name
    May 28 '11 at 9:05
  • There are two definitions of hypervisor ( see en.wikipedia.org/wiki/Hypervisor ). All three virtualization techniques listed above use type-2 hypervisors, and none have the option to run as a type-1.
    – Fake Name
    May 28 '11 at 9:08

VMware Fusion has a nice feature in 3.x called Unity that allows Windows applications to run on the Mac desktop without running in a window that also runs Windows. This means that you could have Word 2010 running with the look and feel of Word 2010 on Windows 7, but as another application Window on your Mac.

Windows must still be booted as a VM - it's just that VMware Fusion hides this. Applications in Unity mode can be pinned to the dock just like regular Mac OS X applications. Launching them launches VMware, which boots the VM and then spawns the application.

This is akin to Wine on Linux, except a full VM of Windows is running - no API translations, full Windows fidelity.

You can alt-tab amongst Mac and Windows apps.

See: http://www.tuaw.com/2007/06/06/vmware-fusion-unity/

  • 1
    Parallels and VirtualBox both offer this 'windowed' mode as well.
    – calum_b
    May 29 '11 at 11:26
  • VMware working great on my MacPro. I can run Windows and Linux at the same time as the Mac OS. Apr 12 '13 at 3:06

This is still true. "Bootcamp", as the name implies, is a way to boot into a non-Apple operating system, and your computer can only boot into one operating system at a time.

If you want to use Windows programs side-by-side with Mac programs, you'll need to use a virtualization program like Parallels or Fusion.

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