A brief history of computing

Starting with a small ad for the $750 Kenbak-1 in the Scientific American magazine in 1971, the personal computer industry has expanded to surpass 1bn machines in use worldwide.

Unveilling the Apple iCloud “cloud computing” service this week, Steve Jobs, chief executive, said the service would herald a “post-PC” world.

“We’re going to demote the PC and the Mac to just be a device,” Mr Jobs said.

As some technologists contemplate the end of the PC era, we examine the 40-year history of personal computing.