The correct answer is valves.The period of first generation was from 1946-1959.The computers of first generation used vacuum tubes as the basic components for memory and circuitry for CPU (Central Processing Unit).These tubes, like electric bulbs, produced a lot of heat and the installations used to fuse frequently.Therefore, they were very expensive and only large organizations were able to afford it.In this generation, mainly batch processing operating system was used. Punch cards, paper tape, and magnetic tape was used as input and output devices.The computers in this generation used machine code as the programming language.The main features of the first generation are ?Vacuum tube technologyUnreliableSupported machine language onlyVery costlyGenerated a lot of heatSlow input and output devicesHuge sizeNeed of ACNon-portableConsumed a lot of electricitySome computers of this generation were ?ENIACEDVACUNIVACIBM-701IBM-650Additional InformationLarge-scale integration (LSI) is the process of integrating or embedding thousands of transistors on a single silicon semiconductor microchip.LSI technology was conceived in the mid-1970s when computer processor microchips were under development.Server Side Includes (SSI) is a simple interpreted server-side scripting language used almost exclusively for the World Wide Web.