Describe how data is represented when a digital medium is used.

What will be an ideal response?

When a digital medium is used to transmit digital data (between the serial communication port, COM1, of two PCs, for example), some form of digital waveform is used to represent the data. A digital waveform is a waveform that contains only two different voltages. Inside the computer, these two voltages are usually 0 volts and 5 volts. Outside the computer, plus and minus 12 volts are often used for digital waveforms. Refer again to Figure 1-3. The non-return to zero (NRZ) technique simply uses a positive voltage to represent a 0 and a negative voltage to represent a 1. The signal never returns to zero.