Vacuum-tube computers, now called first-generation computers, are programmable digital computers using vacuum-tube logic circuitry. They were preceded by systems using electromechanical relays and followed by systems built from discrete transistors. Some later computers on the list had both vacuum tubes and transistors. This list of vacuum-tube computers is sorted by date put into service: See also List of transistorized computers History of computing hardware References Vacuum tube computers Computers, list of vacuum tube