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The telegraph is a machine used to transmit coded information by electrical signals. -
A computer is a machine or device that performs processes, calculations, and operations according to instructions provided by a software or hardware program. -
The telephone is a telecommunication device created to transmit acoustic signals at a distance by means of electrical signals. -
The radio is a means of communication that is based on the sending of audio signals through radio waves. -
The television is a system of transmission of images and sound at a distance through Hertian waves. -
The mobile phone is a wireless handheld device that allows users to make and receive calls. -
A tablet is a wireless portable personal computer with a touch screen interface.