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Control-Alt-Delete

If you’re a PC user, you’ve probably used it: “Control-Alt-Delete.” The well-known keystroke combo can get you out of a tight spot when your machine freezes up, but have you ever stopped to wonder how this technique actually came to be?

Software engineer David J. Bradley is the man behind this ubiquitous invention. Born in 1949, Bradley received a B.E.E. degree in 1971 from the University of Dayton, (Ohio). He went on to Purdue University in West Lafayette, Indiana, where he completed an M.S. degree in 1972 and Ph.D. in 1975, both in electrical engineering. Upon graduation he went to work for IBM in Boca Raton, Florida, as senior associate engineer.

At IBM, Bradley was assigned to work on advanced technology for IBM’s Series/1 system. In 1978 he transferred into the entry-level systems department where he developed the I/O system for the System 23 Datamaster.

In 1980, Bradley became part of a team of 12 engineers who came to be known as the “Original 12” responsible for building the IBM Personal Computer. Specifically, his work was to be on the PC’s ROM BIOS (Basic Input/Output System) code, which helped to make the modern PC possible. This is the built-in program containing a computer’s startup commands and operating directives. For this he was promoted to senior engineer and began managing BIOS and diagnostics for IBM’s PC XT.

In 1981, Bradley’s team had been looking for a simple way that computer users could “reboot” the personal computer without shutting it off should it freeze or fail unexpectedly. After a computer was “powered down,” the machine needed a few seconds to “rest” before “powering up” again to avoid damaging the hardware. This way, it could reboot itself on its own time, so to speak.

Intending its use only for programmers and those writing computer documentation, Bradley wrote some code that allowed the depression of the keys “Control,” “Alt” and “Delete” all at the same time to accomplish the restart function. He chose the key combination, which later came to be known as “the three-finger salute,” because it would be very difficult to hit these keys together by accident. The inner workings of the computer also required that he choose two shift keys to make it work, and with the “delete” key being located at the other end of the keyboard, this combo was safe and simple.

Bradley has said it only took him a few minutes to come up with the idea, but he thought at the time it would only be used internally, or by engineers. This did occur, as the technique proved helpful to software developers, technical writers and engineers who needed to restart their machines many times, but then Microsoft adopted it for the Windows operating system, for use when software fails. The technique is still built into the system today. It helps users power down correctly and also to handle administrative functions by calling up the “Task Manager” feature.

Though “Control-Alt-Delete” helped make Bradley famous, his accomplishments over his 28-year career with IBM are numerous and varied. In 1983 he formed the Personal Systems Architecture Department and the following year he began managing the Personal System 2 Model 30. In 1986 he began working on IBM’s Corporate Development Staff and a year later became manager of advanced processor design, developing IBM’s 486/25 Power Platform and the PS/2 Models 90 and 95. In 1991 he became manager of systems architecture for the Entry Systems Technology group. In 1992 he became the architecture manager for the group that developed the personal computer using the PowerPC RISC microprocessor.

In 1993, Bradley was named manager of architecture for the PC group in October 1993 and continued in that position after moving to North Carolina in 1995. Along the way he also taught electrical and computer engineering at Florida Atlantic and North Carolina State universities. He wrote the book “Assembly Language Programming for the IBM Personal Computer” and holds seven U.S. patents.

In January, 2004, Bradley retired from IBM as Senior Technical Staff Member; Manager, PC Architecture. As of this writing, he continues to consult for the company’s facility in Research Triangle Park, N.C.

[February 2005]