Figure B.1 gives a sense of the power of Moore's law. In the early 1970s, one could fit only 2,300 transistors into an Intel chip. Today, a single Intel quad core i7 chip contains about a billion transistors, and high-end chips used in workstations or servers (Xeon chips) can contain double that number. Over the period 1997-2015, the US consumer price index (CPI) for personal computers fell by nearly 95 per cent, while the corresponding index for all items purchased by consumers has risen by nearly 50 per cent.