After Babbage's unsuccessful attempts little progress was made until the 1930s when Zuse constructed his first computer in his parents living room. He built the first universal binary computer, the Z3, in 1941. Whereas Zuse had constructed his Z3 alone, the first large universal computer ENIAC was constructed by a 50 man team at the University of Pennsylvania and completed in 1945. This computer had to be programmed by wiring up control panels. In the 1950s the wired up control panels were replaced by punched cards. Yet computers were often designed, constructed, programmed, operated and maintained by the same people and operating systems were unheard of.