Q. What is the basic working of Decoders?
An n-bit binary code is capable of encoding up to 2ⁿ distinct elements of information. A decoder is a combinational network that decodes (converts) the n-bit binary-coded input to m outputs (m ≤ 2n). The block diagram of a 3-bit to 8-element decoder is shown in Figure (a), wherein the three inputs are decoded into eight outputs, one for each combination of the input variables. In the truth table shown in Figure (b), observe that for each in- put combination, there is only one output that is equal to 1 (i.e., each combination selects only one of the eight outputs). The logic diagram of the 3-to-8 decoder is shown in Figure (c).

Decoding is so common in digital design that decoders are commercially available as MSI (medium-scale integration) packages in the form of 2-to-4, 3-to-8, and 4-to-10 decoders. Integrated circuits for decoders are available in different forms.