An encoder is a device, circuit, or program that converts information from one format to another. It accepts one or more inputs and generates a multibit output code. The purposes of encoders include standardization, speed, secrecy, security, and reducing size. There are different types of encoders such as simple encoders, priority encoders, and decimal to binary code encoders. Decoders perform the reverse function of converting a code back into a recognizable number or character.

2. ENCODERS
•An encoder is a device, circuit,
transducer, software program,
algorithm or person that converts
information from one format or code to
another. The purpose of encoder is
standardization, speed, secrecy,
security, or saving space by shrinking
size. They accept one or more inputs
and generate a multibit output code.

3. An encoder is a combinational logic circuit that
generate n output lines from 2n (or less) inputs. It has
the reverse function of the decoder.

4. ADVANTAGES
•To store more data in a given space
•To send more data from source to
destination.
•To detect the errors easily.

5. ENCODER WITH ENABLE INPUT
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E= 1 Start Encoding (Enable the circuit)
E= 0 No Operation (Disable the circuit
E= 0 Start Encoding (Enable the circuit)
E= 1 No Operation (Disable the circuit

6. DECIMAL TO BCD ENCODER

7. LOGIC EQUATION LOGIC DIAGRAM

8. TYPES OF ENCODER
SIMPLE ENCODER
1.) 4 BY 2 ENCODER

9. TRUTH TABLE

10. LOGICAL EXPRESSION
• A = Y2 + Y3
• B = Y1 + Y3
LOGIC DIAGRAM

11. 2.) 8 BY 3 ENCODER
OCTAL TO BINARY ENCODER
TRUTH TABLE
LOGICAL
EXPRESSION
A = D1 + D3 + D5 + D7
B= D2 + D3 + D6 + D7
C = D4 + D5 + D6 +D7

12. LOGIC DIAGRAM

13. PRIORITY ENCODER
• Has more than 1 input which is activated based on priority,
meaning it is used to control interrupt request by acting
according to highest priority.
valid bit indicator

14. TRUTH TABLE

15. LOGIC EQUATION
• K-MAP
• A= D2 + D3
• B= D3 + D1D2
• V= D0 + D1 + D2 + D3

16. LOGIC DIAGRAM

17. 8 BY 3 ENCODER

18. EXAMPLE:

19. EXAMPLE:

20. DECODER
• The process of taking some type of code and determining what it
represents in terms of a recognizable number or character is called
decoding. A decoder is a combinational logic circuit that performs
the decoding function, and produce an output that indicates the
(meaning) of the input code.
• The decoder is called n to m where m < 2n for example two to four
line decoder,

21. • Fig. (1) shows a two to four line decoder and its truth table.

22. LOGIC DIAGRAM

23. THE BCD DECODER
• The BCD decoder converts each BCD code (8421) into one of ten possible
decimal digit indications. It is typically referred to as a 1 of 10 or 4 to 10
lines decoder, although other types of decoder also fall into this category
(such as an Execs – 3 decoder). A list of the ten BCD code words and their
corresponding decoding functions is shown in Table (2). Each of these
decoding functions is implemented with NAND gates to provide active LOW
outputs, as shown in Fig. (2)

24. • The 7442 is an integrated circuit BCD to Decimal decoder. Note
that on this device the inputs are A, B, C, and D where A is the
least significant bit.

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