Modem

A modem, short for modulator-demodulator, is a computer hardware device that converts digital data into a form suitable for transmission over an analog medium such as a telephone line or radio, modulating a carrier signal to encode the data at the sending end and demodulating it to recover the original digital information at the receiving end. AT&T introduced the Bell 103A standard in 1962, an early widely used dial-up modem standard, and by the early 1970s competing designs pushed speeds higher: Vadic's VA3400, introduced in early 1973, achieved full-duplex operation at 1,200 bits per second over an ordinary phone line, and AT&T's own 212A modem followed in November 1976. Modems went on to become the standard means of connecting home computers to the internet through the late twentieth century, before broadband technologies largely replaced them.