Lec-10/logic/decoder & encoder

Decoders & Encoders
Decoder
In a digital system, discrete quantities of information are represented with binary codes. A binary code of n bits can represent up to 2n distinct elements of the coded information. A decoder is a combinational circuit that converts n bits of binary information of input lines to a maximum of 2n unique output lines. Usually decoders are designated as an n to m lines decoder, where n is the number of input lines and m (=2n) is the number of output lines.
Decoders have a wide variety of applications in digital systems such as data demultiplexing, digital display, digital to analog converting, memory addressing, etc.
Encoders
An encoder is a combinational network that performs the reverse operation of the decoder. An encoder has 2n or less numbers of inputs and n output lines. The output lines of an encoder generate the binary code for the 2n input variables. Figure 4 illustrates an eight inputs/three outputs encoder. It may also be referred to as an octal-to-binary encoder where binary codes are generated at outputs according to the input conditions.