Mainframe computers are large computers designed to be central sources of digital computer operations and to provide data storage for large amounts of information. The name came from the room-sized first computers, such as the Mark I at Harvard University and ENIAC at the University of Pennsylvania. The main frame was the case that held it.

The first generation of commercial computers was entirely mainframe, beginning with UNIVAC (UNIVersal Automatic Computer), built in 1950 by J. Presper Eckert and John Mauchly and manufactured by Remington Rand. These computers had thousands of bulky vacuum tubes for processing, mercury delay lines or magnetic drums for memory, punched cards for input and output, miles of wiring, and large power requirements. They were used for individual data-processing problems. UNIVAC became famous when it accurately predicted the outcome of the 1952 presidential election. Other typewriter, pocket calculator, and control equipment companies quickly entered...