Introduction to Digital Systems: Modeling, Synthesis, and Simulation Using VHDL

1.3 HISTORY OF DIGITAL SYSTEMS

One of the earliest digital systems was the dial telephone system. Pulses generated by activating a spinning dial were counted and recorded by special switches in a central office. After all the numbers had been dialed and recorded, switches were set to connect the user to the desired party. A switch is a digital device that can take one of two states: open or closed.

In 1939, Harvard University built the Harvard Mark I, which went into operation in 1943. It was used to compute ballistic tables for the U.S. Navy. In the next few years, more machines were built in research laboratories around the world. The ENIAC (Electronic Numerical Integrator and Computer) was placed in operation at the Moore School of Electrical Engineering at the University of Pennsylvania, component by component, beginning with the cycling unit and an accumulator in June 1944. This was followed in rapid succession by the initiating unit and function tables in September 1945 and the divider and square-root unit in October 1945. Final assembly of this primitive computer system took place during the fall of 1945.

The first commercially produced computer was Univac I, which went into operation in 1951. More large digital computers were introduced in the next decade. These first-generation computers used vacuum tubes and valves as primary electronic components and were bulky, expensive, and consumed immense amounts of power. The invention of the transistor in 1948 at the Bell Telephone ...