The major changes in computer design from the 1950s to the 1970s were marked by the transition from the use of vacuum tubes to transistors, integrated circuits, and ultimately microprocessors. After each progression, computers became smaller, more reliable, and encouraged the development of compatible computers. This, in addition to the availability of more functional software, has led to an increase in the use of personal computers in business, government, academic institutions and the military. It is important to note that the IBM System/360 Model 40 computer had 128 KB of memory (Rattenbury), whereas it is common for our computers today to have around 4,000,000 kilobytes, or 4 gigabytes of memory. Computer input and output devices also evolved from punch cards and magnetic tapes to keyboards, monitors, and printers, sparking the development of more advanced technologies, such as touch screens and today's 3D. today.