Since then, he has made several appearances at company and technology events to discuss the priorities of mobile and cloud products, as he works to shift Microsoft away from its longtime core business of software for personal computers.
Read also:
• New Microsoft boss advised: Pick your battles
• New Microsoft chief: 'I love test cricket'
Nadella has signaled a desire to produce software for rival operating systems like Apple's iOS and Google's Android and has shuffled management in areas like marketing, business development and the Xbox game console.
"We believe management is effectively laying the groundwork for a healthy fiscal year 2015," Daniel Ives, an analyst at FBR Capital Markets, wrote in a note Thursday about Nadella's memo.
When Microsoft agreed to acquire Nokia's handset business in September, the software maker pledged $600 million in annual cost savings for 18 months after the deal closes. Meeting that commitment will probably involve job cuts in areas where the two companies overlap, said the people familiar with Nadella's thinking, who asked not to be identified because the discussions are private.
Other job cuts may result from changes Nadella is making to the engineering organisation, said the people. Engineering teams have traditionally been split between program managers, developers and testers.
Yet with new cloud methods of building software, it often makes sense to have the developers test and fix bugs instead of a separate team of testers, Nadella said in the interview. He is also elevating designers and data scientists to be on par with the engineering team on each product, he said.
Nadella declined to say in the interview whether the changes will result in job cuts and said he would provide more details on the implications of his memo when Microsoft reports fiscal fourth-quarter earnings on July 22. He said some of the changes have already been under way in several groups.
Nadella also defined productivity as corporate and consumer activities. He identified Cortana, Microsoft's voice-controlled personal assistant, as "perhaps the biggest innovation in productivity we've done."
Watch: Microsoft Unveils Larger Surface Tablet
The CEO said he sees the company's operating systems as a cloud OS comprised of Azure, its software for hosting and running apps in the cloud; its Windows software for PCs; as well as Windows for devices and Microsoft's own hardware. He pledged to modernise the company's engineering processes to be faster and rely more on data, as well as making them better at predicting what customers want.
Nadella also stated his commitment to Xbox, even as he listed it as something outside the company's core.
"It's critical to define the core, but it's important to make smart choices on other businesses in which we can have fundamental impact and success," Nadella wrote in the memo. "The single biggest digital life category, measured in both time and money spent, in a mobile-first world is gaming."
Microsoft isn't interested in building hardware to become an equipment maker, Nadella said. Instead, the company will focus on areas where it can define new categories, he said.
In some ways the focus on productivity and platforms harkens back to where Microsoft was in the 1990s when it had two divisions: platforms and applications. The focus on mobile and cloud makes that mission bigger and gives Microsoft more potential to stake out a key role in customers' lives, Nadella said in the interview.
"That core sensibility we have has to be redefined in sensible ways," he said. "It's a much more bold ambition on our core than we ever had."
- Bloomberg