Encoder

Encoder 

A digital circuit like a calculator converts decimal inputs (0-9) to binary using an encoder for processing. After operations like addition with a binary adder, the binary output is converted back to decimal and displayed, typically with a 7-segment display. Computers use similar encoders to convert input data to ASCII or BCD. 

BCD Encoder 

An encoder is a combinational circuit that converts standard input into coded signals. A BCD encoder converts decimal numbers (0-9) into BCD code using ten switches. For example, pressing '0' outputs ABCD = 0000, and pressing '3' outputs ABCD = 0011. 

Circuit Diagram: 

Truth Table: 

Decoder 

A decoder is a combinational logic circuit that converts an encoded signal back to its original form. For example, a BCD decoder converts BCD code into a decimal number. It performs the reverse function of an encoder, accepting coded inputs and generating the desired standard output.  

BCD to Decimal Decoder 

The select lines of a demultiplexer can serve as BCD inputs (DCBA), with ten outputs (Y0 to Y9). This setup is called a 1-of-10 decoder, as only one output is high at a time. For active-low output, replace AND gates with NAND gates. 

Circuit Diagram: 

Working: When BCD input is DCBA = 0000, the first AND gate is enabled, making Y₀ = 1. For DCBA = 0001, the second AND gate is enabled, making Y₁ = 1. Each BCD input produces one high output. For DCBA = 1001 (9), Y₉ will be high.