History of the Personal Computer

By David J. “Dr. Dave” Bradley

Today, the personal computer (PC) is ubiquitous in homes and offices. But that wasn’t always the case. The PC dates back to 1975, when it was no more than a kit a hobbyist put together.

This presentation is an amusing examination of the PC’s history, with enough detail to interest the techies but also social history of interest to all.

Tracing the early history of PCs, from its founders through the IBM Personal Computer family of machines, this talk discusses the false starts and missteps in the PC’s creation, and common themes in the PC industry — from market forecasting (or lack thereof) to the influence of standards on overall business growth, the original PC’s design, and the stories of how the computers came about.

Also detailed:

• The very first IBM PC, as delivered by Dave to Microsoft, looked like a science fair project gone bad.
• Bill Gates’ contributions to the PC.
• The all-conquering IBM sales force in a story about the sound system of the PC.
• The problems that arose in developing a family of systems, and some of the interesting solutions that followed.

Getting to Know Dr. Dave

The IBM Personal Computer and its family of systems very much involve Dr. Dave Bradley — one of the “original 12” engineers central to the PC’s development in 1980.

Dave is best known as the inventor of the infamous three-key sequence, Ctrl + Alt + Del. He describes the way it came about, Bill Gates’ contribution to it, and the continuing role it plays in the world today. In short, “David Bradley…saved Bill Gates’ derriere.”

Dave, who has been described as having “the memory of an elephant and the files of a historian,” holds a Ph.D. in Electrical Engineering from Purdue University and worked at IBM from 1975 until he retired in 2004. In addition to the original IBM PC, Dave worked on IBM’s PCs throughout his career. He founded IBM’s Personal Computer Architecture department and worked frequently in architecture and technology areas. 

Dave’s work was always on IBM’s smallest systems – Series/1 minicomputer, System/23 DataMaster, and the IBM family of PCs.

As one of the IBM PC’s “original 12” engineers, he was responsible for the Basic Input/Output System (BIOS) of the machine; and for writing code that controlled the display, keyboard, diskette drive, printer, and other hardware devices of the system. In doing so, he created the infamous three key sequence: Ctrl + Alt + Del.

Dave purchased and constructed his own PC in 1978, a Digital Group system. He worked on IBM’s System/23 DataMaster, which was the first use of an Intel microprocessor in an IBM system. As the BIOS writer for the IBM Personal Computer, Dave met Microsoft’s Bill Gates, Paul Allen, and Steve Ballmer when he delivered the first PC prototype to Bellevue, Washington, in December 1980. 

Dave was in the middle of the IBM PC development, designing the system architecture, debugging systems in the lab, and delivering prototype systems to software vendors. After the PC was announced, he made technical presentations and sales calls to describe the machine and its uses.

As the PC organization split into three development groups, Dave first worked on the IBM PC XT, which added a 10 MB disk to the design. Then, as compatibility became an issue, Dave founded the PC Architecture group to work with the PC AT and PCjr development teams to establish consistency across the products.

He holds several patents related to the PC design, two of which are fundamental to a program’s interaction with the display system and have been so valuable to IBM that Dave received a Corporate Patent Portfolio award in recognition. He also wrote a technical book about the PC, Assembly Language Programming for the IBM PC. 

Dave recently retired from IBM’s xSeries Architecture and Technology department, where he worked on IBM’s family of Intel-based servers. He is an adjunct professor of electrical engineering at North Carolina State University, a subject he has taught since 1976. Dave is the author of two books on PCs and holds 10 patents related to PCs.