Early life

Gates was born in Seattle, Washington, to William H. Gates, Sr. and Mary Maxwell Gates. His family was upper middle class; his father was a prominent lawyer, his mother served on the board of directors for First Interstate BancSystem and the United Way, and her father, J. W. Maxwell, was a national bank president. Gates has one older sister, Kristi (Kristianne), and one younger sister, Libby. He was the fourth of his name in his family, but was known as William Gates III or "Trey" because his father had dropped his own "III" suffix.^[10] Early on in his life, Gates's parents had a law career in mind for him.^[11]

At thirteen he enrolled in the Lakeside School, an exclusive preparatory school.^[12] When he was in the eighth grade, the Mothers Club at the school used proceeds from Lakeside School's rummage sale to buy an ASR-33 teletype terminal and a block of computer time on a General Electric (GE) computer for the school's students.^[13] Gates took an interest in programming the GE system in BASIC and was excused from math classes to pursue his interest. He wrote his first computer program on this machine: an implementation of tic-tac-toe that allowed users to play games against the computer. Gates was fascinated by the machine and how it would always execute software code perfectly. When he reflected back on that moment, he commented on it and said, "There was just something neat about the machine."^[14] After the Mothers Club donation was exhausted, he and other students sought time on systems including DEC PDP minicomputers. One of these systems was a PDP-10 belonging to Computer Center Corporation (CCC), which banned four Lakeside students—Gates, Paul Allen, Ric Weiland, and Kent Evans—for the summer after it caught them exploiting bugs in the operating system to obtain free computer time.^[15]

At the end of the ban, the four students offered to find bugs in CCC's software in exchange for computer time. Rather than use the system via teletype, Gates went to CCC's offices and studied source code for various programs that ran on the system, including programs in FORTRAN, LISP, and machine language. The arrangement with CCC continued until 1970, when it went out of business. The following year, Information Sciences Inc. hired the four Lakeside students to write a payroll program in COBOL, providing them computer time and royalties. After his administrators became aware of his programming abilities, Gates wrote the school's computer program to schedule students in classes. He modified the code so that he was placed in classes with mostly female students. He later stated that "it was hard to tear myself away from a machine at which I could so unambiguously demonstrate success."^[14] At age 17, Gates formed a venture with Allen, called Traf-O-Data, to make traffic counters based on the Intel 8008 processor.^[16]

Gates graduated from Lakeside School in 1973. He scored 1590 out of 1600 on the Scholastic Aptitude Test^[17] and subsequently enrolled at Harvard College in the fall of 1973.^[18] Prior to the mid 1990s, an SAT score of 1590 was equivalent to an IQ of about 170 (roughly the one in a million level),^[19] a figure that would frequently be cited by the press.^[20] While at Harvard, he met his future business partner, Steve Ballmer, whom he later appointed as CEO of Microsoft. He also met computer scientist Christos Papadimitriou at Harvard, with whom he collaborated on a paper about algorithms.^[21] He did not have a definite study plan while a student at Harvard^[22] and spent a lot of time using the school's computers. He remained in contact with Paul Allen, joining him at Honeywell during the summer of 1974.^[23] The following year saw the release of the MITS Altair 8800 based on the Intel 8080 CPU, and Gates and Allen saw this as the opportunity to start their own computer software company.^[24] He had talked this decision over with his parents, who were supportive of him after seeing how much Gates wanted to start a company.[