ENIAC — Early Electronic Numerical Integrator and Computer

Design and components

ENIAC occupied a large room and was composed of modular panels containing thousands of components. It used nearly 17,500 vacuum tubes and several thousand diodes, with extensive wiring connecting arithmetic units, accumulators, and control panels. The hardware required substantial electrical power and cooling; maintenance was a regular part of operation because vacuum tubes were prone to failure.

Programming and operation

Programming ENIAC was done by setting plugboards and switches and by rewiring cable connections; that is, programs were physically configured rather than stored in memory. Teams of operators—most notably a group of women mathematicians who became known as the ENIAC programmers—translated mathematical problems into the machine's wiring and sequence of operations. Later modifications introduced more flexible sequence control techniques that anticipated stored-program concepts.

Uses and historical importance

The first practical applications were military and scientific calculations, including artillery firing tables. ENIAC's speed and electronic architecture showed a clear path beyond mechanical calculators and early electromechanical devices. Its construction stimulated commercial ventures and inspired further research that led to smaller, more reliable, and more easily programmed machines.

Notable facts and legacy

• Designed by John Mauchly and J. Presper Eckert, who later formed a computer company.
• Used a plugboard programming model rather than a stored program at first.
• Required continuous maintenance and significant electrical infrastructure.
• Recognized as a milestone in the transition to electronic computing and studied in histories of computing.

For introductory and archival materials, see contemporary summaries and museum collections: technical overview, component lists, and photographic records. Additional educational resources and timelines are available from institution pages and computing histories: timeline, further reading.