Dual operating allows best of both worlds - Stuff.co.nz

Samsung Ativ Q PC

TWO-IN-ONE: Samsung's Ativ Q PC runs both Windows and Android operating systems.

We all know the personal computer is doomed, and tablets are the future, right?

Presumably that explains the Asus Transformer AiO P1801 and the Samsung Ativ Q, two PCs that run both stodgy old Windows and tablet powerhouse Android, so that between drafting memos you can chill with Angry Birds or whatever it is the kids play these days.

Now it isn't that unusual for a computer to have several operating systems installed: Windows, OS X and free operating systems like Linux and FreeBSD can live together on the same hard disk, but if you want to switch from one to the other you have to shut down the computer and reboot into the other system. These new machines don't need that: you just press a button to flip back and forth between Windows and Android.

But hang on a minute. One of the chief jobs of an operating system is to manage all of the computer's resources. How then can a computer run two operating systems simultaneously? That sounds like a nasty power struggle that will end in sparks.

One way to make the figures balance is to really have two computers inside the case, each running its own operating system and each largely independent but connected to and aware of the other. This one-box, two-computers solution may sound a bit odd but used to be fairly common back when the computing ecosystem was more diverse and programs were often locked to particular processors. Asus gets their machine to run Android alongside Windows in this way.

But dual operating systems are possible without extra hardware. An operating system manages the resources of a computer - but who said that had to be a real computer? An emulator is a special program that runs on one computer (the host) and simulates another computer (the guest) in software. As long as the emulator carries out all the operations of the guest computer and mimics its keyboard, screen and other peripherals, software running inside the guest - including the operating system - won't even know it's not on a physical computer.

Complete emulation in software can be very slow but if the host and guest are the same kind of computer then it's possible to speed things up. Most parts of any program are mundane things like simple arithmetic and byte shuffling. The host can perform those operations directly and quickly, with the slow emulator stepping in only when the guest needs to do things like display output.

This approach is called virtualisation and with co-operation from the host processor, guest software can run close to full speed. From the outside it can look like the two operating systems are equal partners, but really the host is in charge and the guest is just a puppet leader. Virtualisation is already common (as a way to run PC applications on a Mac, for instance) and it is how Samsung's Ativ Q runs Android and Windows.

So there - two ways to have dual operating systems without having duelling operating systems. Sometimes you can have your cake and eat it too.

- © Fairfax NZ News



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