In 1944 the first digital computer appeared. In 1946 American scientists constructed an electronic numerical integrater and calculator (ENIAC), the world's first automatic, general-purpose, electronic computer. ENIAC, which consisted of more than 18,000 valves, filled an entire room and could handle 5,000 calculations per second. By the 1950s IBM had begun to mass-produce computers, introducing the first personal computer in 1981. In 1969 the Internet was born; CD-Roms appeared in 1991.