The A-B Computer used dynamic storage for its main memory, requiring periodic "refresh" to remind if of its binary state, as do today's dynamic RAM chips. Atanasoff considered using relays, magnetic core memory, vacuum tubes, and charged capacitors to store each bit of memory; he finally decided on the latter, on the basis of the cost/performance.
The Atanasoff-Berry Computer was the first electronic digital computer. The original ABC was dismantled decades ago. Ames Laboratory, using private funding, is building a working replica of this historically important invention.
The 1946, ENIAC Computer
was long thought to have been the first electronic computer and the inventors, J. Presper Eckert and John W. Mauchly were the first to patent a digital computing device - - but a 1973, patent infringement case (Sperry Rand Vs. Honeywell), voided the ENIAC patent as a derivative of Atanasoff's invention.