The correct order is:
1. Vacuum Tube: First generation 1940 - 1956 The first computer systems used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms.
2. Transistors: Second generation 1956 - 1963 The world would see transistors replace vacuum tubes in the second generation of computers.
3. Integrated circuits: Third Generation. 1965 - 1971. The computers of third generation used Integrated Circuits (ICs) in place of transistors.
4. Computer chips.