Hoverbots

In the 20th century, computers went from the size of several rooms and worth millions of dollars when they were first invented to small enough to fit in a pocket and cost less than a week's wages for most people.
In the 21st century, computers continued to become less expensive and more powerful, able to rest on their owner's wrist, or even inside their owner's ear. Free computer consoles are available in every city for public use.
In the 22nd century, contact lenses have a significant amount of computing power. Disposable / reusable computers are lying around everywhere. If you don't see one, check any public trash bin. It's about the size of a credit card.
In the 23rd century, to reduce waste, public computers are given self-mobility, the shape of drone helicopters with nearly silent flight blades. Just reach up and a hoverpad will fly into your hand and let you use it as a computing pad.
In the 24th century, nearly microscopic robots can connect like toy blocks to form usefull tools and other shapes. The small but impressive computing power of each micro machine combines with a nearly neural network of others to add up to an impressive computer that can take the shape of any tool or structure or mechanism desired. Thye smallest building-block of this material is called a Nanobot, and it is at your service.
By the late 25th century the favorite form of nanobots is the retro look of the hoverpad, (also called "hoverbot"), floating about your head like in the old stories, and you just have to reach out to have all the computing power, sensors, and tools you could want.