Workmen mounting core memory unit into JOHNNIAC, c. 1957
Credit: The Rand Corporation

One-of-a-Kinds

The first automatic electronic calculators were hand-wired one-of-a-kind machines. Their designers struggled to find effective architectures but had only primitive and unreliable components to work with. ENIAC was an early programmable electronic calculator that stunned the world with its speed and complexity compared to mechanical predecessors. ENIAC’s designers went on to build a stored-program calculator called “Univac,” which was the first commercial electronic digital computer ever made. Other early computers, like Johnniac and the WISC, were special research machines. MIT’s Whirlwind was particularly influential because it led to the invention of core memory, which was a key enabling technology in the history of computers.