FORTUNE — Having apparently concluded that Microsoft’s (MSFT) new tablet computer initiative — dubbed Surface — is not in fact a “hoax,” Daring Fireball‘s John Gruber took a hard look Wednesday at the company’s decision to turn against its manufacturing partners and build its own hardware.
The heart of Gruber’s analysis is some math posted earlier in the day by Asymco‘s Horace Dediu.
Dediu calculated that the software licenses for Windows and Office generate about $78 in operating profit per PC sold. Apple (AAPL), by contrast, generates about $178 per unit operating profit just from the iPad. Microsoft used to make it up in volume, but tablet sales are on a trajectory to overtake sales of traditional PCs, which are in decline.
That, writes Gruber, is why Microsoft has decided to compete with the manufacturers that have been its partners since the dawn of the PC era:
Its a thoughtful post. You can read it in full here.