ILLIAC (Illinois Automatic Computer) is the name of a series of mainframe computers built between 1951 and 1974, taking its name from the University of Illinois, where the first computer in the series was built.
In the late 1940s, development work for computers was carried out at the University of Illinois according to the concept presented by John von Neumann and others (First Draft Report on the EDVAC, 1945, Von Neumann Architecture). The result was the ORDVAC. This was followed by an order for another computer, the Illiac I, which went into service in September 1952.
The Illiac I followed the same design as the ORDVAC, had 2800 electron tubes and a drum memory. It was in operation until 1963.
A 5-bit aperture strip was used to store the program.