David Bradley (engineer)
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David J. Bradley (born 4 January 1949) is one of the twelve engineers who worked on the original
IBM PC The IBM Personal Computer (model 5150, commonly known as the IBM PC) is the first microcomputer released in the List of IBM Personal Computer models, IBM PC model line and the basis for the IBM PC compatible ''de facto'' standard. Released on ...
, developing the computer's ROM BIOS code. Bradley is credited for implementing the "
Control-Alt-Delete Control-Alt-Delete (often abbreviated to Ctrl+Alt+Del and sometimes called the "three-finger salute" or "Security Keys") is a computer keyboard command on IBM PC compatible computers, invoked by pressing the Delete key while holding the Control ...
" (Ctrl-Alt-Del) key combination that was used to
reboot In computing, rebooting is the process by which a running computer system is restarted, either intentionally or unintentionally. Reboots can be either a cold reboot (alternatively known as a hard reboot) in which the power to the system is physi ...
the computer. Bradley joined IBM in 1975 after earning his doctorate in electrical engineering from Purdue University with a dissertation on computer architectures.  


Education

Bachelors, Electrical Engineering, University of Dayton (Ohio), 1971. Master of Science, Electrical Engineering, Purdue University, 1972. PhD, Electrical Engineering, Purdue University, 1975.


Control-Alt-Delete

According to Bradley,
Control-Alt-Delete Control-Alt-Delete (often abbreviated to Ctrl+Alt+Del and sometimes called the "three-finger salute" or "Security Keys") is a computer keyboard command on IBM PC compatible computers, invoked by pressing the Delete key while holding the Control ...
was not intended to be used by end users, originally—it was meant to be used by people writing programs or documentation, so that they could reboot their computers without powering them down. This was useful since after a computer was powered down, it was necessary to wait a few seconds before powering it up again to avoid potential damage to the
power supply A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, electric current, current, and frequency to power ...
and hard drive. Since software developers and technical writers would need to restart a computer many times, this key combination was a big time-saver. David Bradley and Mel Hallerman chose this key combination because it is practically impossible to accidentally press this combination of keys on a standard original IBM PC keyboard. However, the key combination was described in IBM's technical reference documentation and thereby revealed to the general public. At the 20th anniversary of the
IBM PC The IBM Personal Computer (model 5150, commonly known as the IBM PC) is the first microcomputer released in the List of IBM Personal Computer models, IBM PC model line and the basis for the IBM PC compatible ''de facto'' standard. Released on ...
on August 8, 2001 at The Tech Museum, while on a panel with
Bill Gates William Henry Gates III (born October 28, 1955) is an American businessman and philanthropist. A pioneer of the microcomputer revolution of the 1970s and 1980s, he co-founded the software company Microsoft in 1975 with his childhood friend ...
, Bradley said, ''"I have to share the credit. I may have invented it ontrol-Alt-Delete but I think Bill made it famous."'' Multiple-key reboot had been introduced by Exidy, Inc., in 1978, for its
Sorcerer Sorcerer may refer to: Magic * Sorcerer (supernatural), a practitioner of magic that derives from supernatural or occult sources * Sorcerer (fantasy), a fictional character who uses or practices magic that derives from supernatural or occult sou ...
Z80 computer. It provided two Reset buttons, which must be pressed simultaneously to achieve reboot. In March 1980, the multiple-key reboot concept had been introduced for the Apple II by Videx in its VideoTerm display card add-on, requiring Control-Reset, rather than Reset alone, to reboot the machine. The innovation was noted and well received at the time.


Other accomplishments

Bradley is the author of ''Assembly Language Programming for the IBM Personal Computer'' (Simon & Schuster, , January 1984), also released in French as ''Assembleur sur IBM PC'' (Dunod, ), Russian ("Radio" Publishing House, Moscow), and Bulgarian ("Technica" Publishing house, 1989). Bradley holds seven U.S. patents. Bradley has been adjunct professor of electrical and computer engineering at
Florida Atlantic University Florida Atlantic University (Florida Atlantic or FAU) is a Public university, public research university with its main campus in Boca Raton, Florida, United States. The university is a member of the State University System of Florida and has s ...
and at
North Carolina State University North Carolina State University (NC State, North Carolina State, NC State University, or NCSU) is a public university, public Land-grant university, land-grant research university in Raleigh, North Carolina, United States. Founded in 1887 and p ...
. Much of Bradley's career has been at
IBM International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...
. 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. He worked on the Series/1 system. In 1978 he developed the I/O system for the System/23 Datamaster. In 1980, Bradley was one of twelve engineers developing the first IBM Personal Computer. Bradley developed the
ROM Rom, or ROM may refer to: Biomechanics and medicine * Risk of mortality, a medical classification to estimate the likelihood of death for a patient * Rupture of membranes, a term used during pregnancy to describe a rupture of the amniotic sac * ...
BIOS In computing, BIOS (, ; Basic Input/Output System, also known as the System BIOS, ROM BIOS, BIOS ROM or PC BIOS) is a type of firmware used to provide runtime services for operating systems and programs and to perform hardware initialization d ...
. That got him promoted to manage the BIOS and diagnostics for the
IBM PC/XT The IBM Personal Computer XT (model 5160, often shortened to PC/XT) is the second computer in the IBM Personal Computer line, released on March 8, 1983. Except for the addition of a built-in hard drive and extra expansion slots, it is very simi ...
. In 1983 Bradley formed the Personal Systems Architecture Department. In 1984, he helped manage development of the Personal System/2 Model 30. In November 1987, Bradley became manager of advanced processor design. His group developed the 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 a personal computer using the
PowerPC PowerPC (with the backronym Performance Optimization With Enhanced RISC – Performance Computing, sometimes abbreviated as PPC) is a reduced instruction set computer (RISC) instruction set architecture (ISA) created by the 1991 Apple Inc., App ...
RISC In electronics and computer science, a reduced instruction set computer (RISC) is a computer architecture designed to simplify the individual instructions given to the computer to accomplish tasks. Compared to the instructions given to a comp ...
microprocessor A microprocessor is a computer processor (computing), processor for which the data processing logic and control is included on a single integrated circuit (IC), or a small number of ICs. The microprocessor contains the arithmetic, logic, a ...
. In 1993, he returned to be the manager of architecture in the PC group. On January 30, 2004, Bradley retired from IBM. Bradley wrote about the development of the IBM PC, including Control-Alt-Delete, in the August 2011 issue of the IEEE's ''Computer'' magazine.


References


External links


The History of IBM
- about.com

{{DEFAULTSORT:Bradley, David Living people 1949 births IBM employees North Carolina State University faculty University of Dayton alumni