Introducing Computer Architecture

The architectures of automated computing systems have evolved from the first mechanical calculators constructed nearly two centuries ago to the broad array of modern electronic computer technologies we use directly and indirectly every day. Along the way, there have been stretches of incremental technological improvement interspersed with disruptive advances that drastically altered the trajectory of the industry. We can expect these trends to continue in the coming years.

In the 1980s, during the early days of personal computing, students and technical professionals eager to learn about computer technology had a limited range of subject matter available for this purpose. If they had a computer of their own, it was probably 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 the 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 early generations in terms of computing power, memory size, disk space, graphics performance, and communication ability. These capabilities enable modern PCs to easily perform tasks that would have been inconceivable on early PCs, such as the real-time generation of high-resolution 3D images.

Companies offering web services to hundreds of millions of users construct vast warehouses filled with thousands of tightly coordinated computer systems capable of responding to a constant stream of user 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 with a presentation of some key historical computing devices and the leaps in technology associated with them. We will then examine some significant modern-day trends related to technological advances and introduce the basic concepts of computer architecture, including a close look at the 6502 microprocessor and its instruction set. The following topics will be covered in this chapter:

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