In 1946, John Mauchly and John Presper Eckert developed the ENIAC (Electrical Numerical Integrator And Calculator).
It weighed more than 30 tons, covered 1800 square feet (167 Sqare Meter) of floor space, and consumed 150 kilowatts of electric power. The ENIAC contained about 18,000 vacuum tubes, 70,000 resistors, 7,200 crystal diodes, 10,000 capacitors, 1,500 relays and around 5 million hand-soldered joints.
IBM's launch of the Personal Computer (IBM 5150) in 1981 set the industry standard for personal computing. It's weight was less 3,000 times and speed 400 times greater than ENIAC.
More detail about ENIAC :
ENIAC Wikipedia
The History of the ENIAC Computer