Small number of 7-segment LED displays are interfaced to microprocessor through BCD to 7-segment decoder/driver and I/O parts. When number increases the techniques are not economical. For example, to display 10 digits 10 decoder/drive and five 8-bit I/O ports are required.
To reduce the number of interfacing components a technique known as multiplexing is used when large number of digits or alphanumeric characters are to be displayed.