SEATTLE — Microsoft says a half billion devices are now running Windows 10, its latest operating system.

That’s up from 400 million disclosed last September, but far short of a goal of 1 billion by 2018. Microsoft has already acknowledged it won’t hit 1 billion in time. Getting halfway has taken nearly two years.

Windows 10 represents a comeback for Microsoft after a disastrous Windows 8 launch and heavy competition from phone systems such as Apple’s iOS and Google’s Android. Getting more devices on Windows 10 will help encourage companies to make more apps and services for it.

CEO Satya Nadella disclosed the figure Wednesday at a Microsoft conference in Seattle.

After getting Microsoft on track to prioritizing mobile devices and internet-based services, Nadella says artificial intelligence will get a bigger focus.