Learning Computer Architecture with Raspberry Pi

Chapter 2

Recapping Computing

NOTE: YOU MAY already know the material in this chapter. Anyone who’s taken any coursework in computing, or played around with computers and programming on their own, has at least a modest grasp of what we present here. This chapter is a broad and very high-level overview of what computers do and what parts of the computer are used to do it. You’ll know within a few pages whether it’s useful for you or not. If it isn’t, feel free to skip directly to Chapter 3.

Although we created computers to do calculations, computers are not calculators. We’ve had calculators for a very long time. The abacus is known to have been used by the Persians as early as 600 BCE, and it was probably in use earlier than that. The precursor to the slide rule, called “Napier’s Bones”, was invented by John Napier in 1617. The very first mechanical calculator, the Pascaline, was invented by Blaise Pascal in 1642—when he was only 19! Better and more elaborate mechanical calculators were devised over the years until very recently, when digital calculators shoved mechanical and analogue calculators onto history’s high shelf.

Charles Babbage is usually credited with the idea of programmability in calculation. He was too poor and his “analytical engine” too complex for him to construct it in 1837, but his son built and demonstrated a more modest version of the machine in 1888. However, it wasn’t until the 1930s that the ideas underlying modern computing began to be understood fully. ...