The ENIAC  (Electronic Numerical Integrator and Computer), introduced at  the University of Pennsylvania  in 1946, was the world's first electronic  digital computer.   Weighing 30 tons and filling a 1000 sq. ft. room, the ENIAC consisted of 42 panels.  Each panel was 9 feet tall, 2 feet wide, and 3 feet thick.  The machine contained 19,000 vacuum tubes, 1500 relays, and several hundred thousand resistors, capacitors, and conductors.   There were 20 accumulators, each capable of storing a 10 digit number.  The ENIAC could perform about 5000 additions or 50 multiplications in one second. The clock speed was 100kHz.  Programs were entered by setting switches on a "plugboard."