Code: The Hidden Language of Computer Hardware and Software, First Edition

Chapter 19. Two Classic Microprocessors

The microprocessor—a consolidation of all the components of a central processing unit (CPU) of a computer on a single chip of silicon—was born in 1971. It was a modest beginning: The first microprocessor, the Intel 4004, contained about 2300 transistors. Today, nearly three decades later, microprocessors made for home computers are approaching the 10,000,000 transistor mark.

Yet what the microprocessor actually does on a fundamental level has remained unchanged. While those millions of additional transistors in today’s chips might be doing interesting things, in an initial exploration of the microprocessor they offer more distraction than enlightenment. To obtain the clearest view of what a microprocessor ...