The first substantial computer was the giant ENIAC machine by John W. Mauchly and J. Presper Eckert at the University of Pennsylvania. ENIAC (Electrical Numerical Integrator and Calculator) used a word of 10 decimal digits instead of binary ones like previous automated calculators/computers. ENIAC was also the first machine to use more than 2,000 vacuum tubes, using nearly 18,000 vacuum tubes. Nonetheless, it had punched-card input and output and arithmetically had 1 multiplier, 1 divider-square roote. which served as adders and also as quick-access (0.0002 seconds) read-write register storage.