Gates, who wrote his first computer program at 13 and scored a perfect 800 on his math S.A.T., has dropped out of Harvard to start what will be the biggest seller of computer software and will make Gates a billionaire before he is 30. Computers are less prone to failure. Computers are smaller. Computers are faster. Computers use less electricity.
Mass production makes computers less expensive.
Timesharing allows users at different terminals to work with the same mainframe at the same time. The most powerful mainframes are called supercomputers. Minicomputers are smaller than mainframes, but larger than personal computes. Personal computers are low-cost, typewriter size computers. Today's personal computers are as powerful as mainframes were before.