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