The first 2,000 years of computing
The Computer History Museum's main exhibition, "Revolution," charts a 2,000-year story from the abacus to the smartphone. The collection holds nearly 90,000 objects, making it one of the largest of its kind in the world. One of its most impressive displays is a working replica of Charles Babbage's Difference Engine No. 2. Designed between 1847 and 1849, the original engine was never built in Babbage's lifetime. The fully constructed machine, built according to his 19th-century plans, consists of 8,000 parts, weighs five tons, and is 11 feet long. This mechanical calculator was designed to tabulate polynomial functions using only addition, a method that eliminated the need for multiplication and division, which were harder to implement with gears.
The museum's collection moves from mechanical computation into the electronic age. Volunteer teams have meticulously restored several landmark machines to full working order. One is the IBM 1401 Data Processing System, the most popular computer of the early 1960s. A team of retired IBM engineers spent over 20,000 hours bringing two of these systems back to life. The 1401 was one of the first computers to use transistors instead of vacuum tubes, making it more compact and reliable. By 1965, half of all computers in the world were 1401s, used for everything from payroll processing to managing inventory.
Supercomputers and video game origins
Another working exhibit is the Digital Equipment Corporation (DEC) PDP-1, a one-ton "minicomputer" from 1959. Its restoration began in 2003 and was completed two years later. The PDP-1 is famous for running one of the first video games, Spacewar!. Developed by Steve Russell and others at MIT in 1962, the game features two player-controlled spaceships in a dogfight around a star's gravity well. The game was a popular demonstration of the computer's real-time graphical capabilities.
The museum also displays famous supercomputers, including the Cray-1. From 1976 to 1982, it was the world's fastest computer. Its unique C-shaped design minimized wire lengths—no segment was longer than three feet—to reduce signal delays. This design also cleverly hid the power supplies in the padded bench surrounding the machine. The Cray-1 operated at 80 MHz and contained over 60 miles of wire. It was used for complex calculations like bomb simulations and cryptography. The museum's collection shows the history of computing, from massive, hand-wired machines to the foundational technology of today's digital world.