问答题 The comparable dates for the computer are harder to tie down, but the first big computer, based on vacuum valves, was built in 1946. The transistor—the first semicon ductor device—was invented at Belt Laboratories in 1948. The first patent for an integrated circuit was filed in 1959. Now, in 1999—50 years after the first one was built—around half of American households own a computer. The pace of introduction has been similar to that of the car.