Philip Donald Estridge was born in Jacksonville, Florida on June23, 1937. His father was a professional photographer.

From 1942 to 1951 he attended St. Paul's School from Kindergarten through eight grade; Jacksonville, Florida, USA. He graduated from Bishop Kenny High School in 1955, and from the University of Florida in 1959.

He married Mary Ann Hellier on September 13, 1958. Three children were born from his marriage: Patricia Ann, Mary Evelyn and Sandra Marie.

Estridge completed a BS in electrical engineering at the University of Florida and joined IBM as a junior engineer in Kingston New York and held positions in the Federal Systems Division, participating in the construction of SAGE . In 1963 he moved to Washington. Working on the manned and unmanned programming support for NASA /Goddard Space Flight Center. In 1969 he moved to Boca Raton, Florida, USA. Joined the General Systems Division and from 1975 - 1979 he was series/1- a mini computer - programming manager.

His efforts to develop the IBM PC began when he became manager of the small Entry Level Systems division in 1980, with the goal of developing a low-cost personal computer to compete against increasingly popular offerings from the likes of Apple , Commodore , and other perceived IBM competitors. His team examined everything created by the other microcomputer companies and combined their best ideas, to produce a relatively low-cost computer. They made a decision to build the machine with "off-the-shelf" parts from a variety of different original equipment manufacturers and countries. They also decided on an open architecture , so that other manufacturers could produce and sell peripheral components and compatible software without purchasing licenses. Estridge published the specifications of the IBM PC, allowing a booming third-party aftermarket hardware business to take advantage of the machine's expansion card slots.

The competitive cost and expandability options of the first model, as well as the cachet of being an IBM product, led to strong sales to both