Analog and Digital Data Transmission
Digital Signals are electrical pulses generated by a computer or a terminal (binary: on-off)
Analog signals are audio tones into which the digital signals are converted for transmission in a telephone network (wave: numerous values)
A modem is a device which converts the direct electrical signals produced by the computer (positive and negative voltages of electricity) to modulated audio signals that can be sent over telephone communications circuits
Connector cable connects the modem to the micro computer (or a terminal)