According to Fortune magazine, in 2010 Ballmer and Gates fell out over taking Microsoft into the hardware space.
Ballmer said there was a “fundamental disagreement” about “how important it was to be in the hardware business,” specifically phones.
“I had pushed Surface. The board had been a little reluctant in supporting it. And then things came to a climax around what to do about the phone business.”
He said he would have moved into the hardware business faster and recognised that what we had in the PC, where there was a separation of chips, systems and software, wasn’t largely going to reproduce itself in the mobile world.
Vole did get into the phone market but was too late to take a forceful position in the market. Ballmer pushed for the eventual $9.5 billion-dollar purchase of Nokia handset unit, and most of the entire value of that deal required a write down.