Drs.
John Mauchly and Presper Eckert thought that a digital
calculator could do the job. So, in April, 1943, through
the Moore School of Engineering at Pennsylvania, they
submitted a memo describing an electronic analyzer that
would compute a trajectory and complete a table within
2 days.
The
army bought the machine and had it constructed at an expenditure
of some 200,000 man-hours. Truly an electronic machine,
the ENIAC (an acronym for Electronic Numerical Integrator
and Calculator) used vacuum tubes. It contained no moving
parts except for input-output gear. It had 500,000 soldered
joints, 18,000 vacuum tubes, 6,000 switches and 500 terminals.
Counting was performed by electronic pulses. The machine
operated on the decimal system. Output was on punched
cards.