<human>:  Why was the ENIAC (computer) so big?
<bot>: The ENIAC was so big because it was the first programmable computer. It took up a whole room. The ENIAC was made of thousands of vacuum tubes, and it was so big that it had to be installed on the floor of the Moore School of Electrical Engineering at the University of Pennsylvania. The ENIAC was the world's first electronic computer, and it was built by John Mauchly and J. Presper Eckert in 1946.