Windows product keys are almost (but not quite) a thing of the past. Sedra And Smith Microelectronic Circuits Pdf on this page. With Windows 10, Microsoft has rewritten the rules for how it performs product activation on retail upgrades of Windows, including the free upgrades available for a year beginning on July 29, 2015. The net result is that clean installs will be much easier--but only after you get past the first one.

OEM activation hasn't changed, nor have the procedures for activating volume license copies. But the massive means that for the near future at least those retail upgrade scenarios are very important. More Windows 10 • • • • • • • • The biggest change of all is that the Windows 10 activation status for a device is stored online. After you successfully activate Windows 10 for the first time, that device will activate automatically in the future, with no product key required.

That's a huge change from previous versions of Windows, which required a product key for every installation. And it's potentially an unwelcome surprise for anyone who tries to do a clean install of Windows 10 without understanding the new activation landscape. I've had some way-off-the-record discussions with people who know a few things about the subject, and I've also done my own testing for the two weeks since Windows 10 was released to the public. Here's what I've learned. Your Windows 10 license is stored online and linked to your device. For more than a decade, one of the keys that Microsoft's activation servers have relied on is a unique ID, which is based on a hash of your hardware. That hash is reportedly not reversible and not tied to any other Microsoft services.

So although it defines your device, it doesn't identify you. Here's how that ID works with Windows 7 or Windows 8: When you activate for the first time, that hashed value (let's call it your installation ID) is recorded in the activation database alongside the product key you entered with the installation.