The transistor was invented in 1947 but did not see widespread use in computers until the late 1950s. The transistor was far superior to the vacuum tube, allowing computers to become smaller, faster, cheaper, more energy efficient, and more reliable than their first-generation predecessors. While the transistor still generated a large amount of heat that damaged the computer, it was a vast improvement over the vacuum tube. Second-generation computers still relied on punched cards for input and printouts for output. Second-generation computers moved from cryptic binary machine language to symbolic, or assembly, languages ​​that allowed programmers to specify instructions in words. High-level programming languages, such as early versions of COBOL and FORTRAN, were also being developed during this period. These were also the first computers to store instructions in memory, moving from magnetic drum technology to magnetic core technology. The first computers of this generation were developed for atomic energy