Old typing machine

A typing machine is a device invented in 19th century, which is used for printing signs on paper by pressing correct buttons. Present day machines - only if they have not been supplanted by computers - are electromechanical, old ones were only mechanical and printed sings with the use of the tape which was moistened with ink. First typing machines used to have alphabetical layout of buttons, however, inventors who modified the device (Thomas Edison) introduced the QWERTY layout, which has been used in computer keyboards until today. This layout was meant to prevent blocking of types.