Chapter 1: Introducing Computer Architecture

The architecture of automated computing devices has evolved from mechanical systems constructed nearly two centuries ago to the broad array of modern electronic computing technologies we use directly and indirectly every day. Along the way, there have been stretches of incremental technological improvement interspersed with disruptive advances that have drastically altered the trajectory of the industry. These trends can be expected to continue into the future.

In past decades, the 1980s, for example, students and technical professionals eager to learn about computing devices had a limited range of subject matter available for this purpose. If they had a computer of their own, it might have been an IBM PC or an Apple II. If they worked for an organization with a computing facility, they might have used an IBM mainframe or a Digital Equipment Corporation VAX minicomputer. These examples, and a limited number of similar systems, encompassed most people's exposure to computer systems of the time.

Today, numerous specialized computing architectures exist to address widely varying user needs. We carry miniature computers in our pockets and purses that can place phone calls, record video, and function as full participants on the Internet. Personal computers remain popular in a format outwardly similar to the PCs of past decades. Today's PCs, however, are orders of magnitude more capable than the first generations of PCs in terms of computing power, memory size, disk space, graphics performance, and communication capability.

Companies offering web services to hundreds of millions of users construct vast warehouses filled with thousands of closely coordinated computer systems capable of responding to a constant stream of requests with extraordinary speed and precision. Machine learning systems are trained through the analysis of enormous quantities of data to perform complex activities, such as driving automobiles.

This chapter begins by presenting a few key historical computing devices and the leaps in technology associated with them. This chapter will examine modern-day trends related to technological advances and introduce the basic concepts of computer architecture, including a close look at the 6502 microprocessor. These topics will be covered:

• The evolution of automated computing devices
• Moore's law
• Computer architecture