The present day digital computers are based on stored-program concept introduced by Von Neumann. In this stored-program concept, programs and data are stored in separate storage unit called memories.

Central Processing Unit, the main component of computer can work with the information stored in storage unit only.

In 1946, Von Neumann and his colleagues began the design of a stored-program computer at the Institute for Advanced Studies in Princeton.This computer is referred as the IAS computer.

The structure of IAS computer is shown in Figure 1.2.