This is where he first became interested in computer programming. The school provided computer time for students. The computers were teletype terminals and Bill had become fascinated with the computer and its capabilities and spent much of his free time experimenting with them. Bill had written a tic-tac-toe program on the BASIC computer that allowed the user to play against the computer. Bill began programming computers at age 13 when he met Paul Allen at Lakeside, two years his senior. The two men showed the same interest in computers and quickly became friends even though they were very different from each other. They both spent much of their free time working on programs. Bill and Paul periodically argued over who would run the lab or who was right. Once, one of their arguments got so bad that Paul banned Bill from the computer lab. Another time, Allen and Gates' computer privileges were revoked because they were using glitches to get more time to use the computers. After their test, they were allowed back into the lab after offering to debug the programs. In the 1970s, when Bill was 15, he and Paul started a company called "Traf-o-Data," a computer program that monitored traffic conditions in Seattle and earned $20,000 for their efforts. Over time, Paul and Bill entertained the idea of ​​starting their own business, but Bill's parents wanted him to go for it..