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Combinational Logic Unit 2
The document discusses multiplexers, encoders, and decoders. It can be summarized as follows: 1) A multiplexer has N control inputs and 2^N data inputs, and selects one of the data inputs to pass to its single output based on the state of the control inputs. 2) Encoders convert numeric inputs into binary codes, while decoders convert binary codes into a single numeric output. 3) Common encoders include binary-coded decimal encoders that convert decimal numbers into 4-bit BCD codes to represent each digit.
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Combinational Logic Unit 2
- 1. UNIT-2 Mohammad Asif Iqbal AssistantProfessor, Deptt of ECE, JETGI, Barabanki
- 2. Multiplexers A multiplexerhas N control inputs 2N data inputs 1 output A multiplexer routes (or connects) the selected data input to the output. The value of the control inputs determines the data input that is selected.
- 3. Multiplexers Z = A′.I0+ A.I1 Data inputs Control input
- 4. Multiplexers Z = A′.B'.I0+ A'.B.I1 + A.B'.I2 + A.B.I3 A B F 0 0 I0 0 1 I1 1 0 I2 1 1 I3 MSB LSB
- 5. Multiplexers Z = A′.B'.C'.I0+ A'.B'.C.I1 + A'.B.C'.I2 + A'.B.C.I3 + A.B'.C'.I0 + A.B'.C.I1 + A'.B.C'.I2 + A.B.C.I3 MSB LSB A B C F 0 0 0 I0 0 0 1 I1 0 1 0 I2 0 1 1 I3 1 0 0 I4 1 0 1 I5 1 1 0 I6 1 1 1 I7
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- 7. Encoder/Decoder Vocabulary ENCODER- adigital circuit that produces a binary output code depending on which of its inputs are activated. DECODER- a digital circuit that converts an input binary code into a single numeric output.
- 8. ENCODERS AND DECODERS A0 A1 A2 A3 A4 A5 A6 A7 ENCODER O0 O1 O2 A0 A1 A2 O0 O1 O2 O3 O4 O5 O6 O7 DECODER ONLYONE INPUT ACTIVATED AT A TIME BINARY CODE OUTPUT BINARY CODE INPUT ONLY ONE OUTPUT ACTIVATED AT A TIME
- 9. THE 8421 BCDCODE • BCD stands for Binary-Coded Decimal. • A BCD number is a four-bit binary group that represents one of the ten decimal digits 0 through 9. Example: Decimal number 4926 4 9 2 6 8421 BCD coded number 0100 1001 0010 0110
- 10. ELECTRONIC ENCODER-DECIMAL TOBCD 0 Decimal to BCD Encoder BCD output Decimal input 0 0 0 0 5 0 1 0 1 7 0 1 1 1 3 0 0 1 1 • Encoders are available in IC form. • This encoder translates from decimal input to BCD output.
- 11. 10 line to4 line Encoder
- 13. ENCODER 1248 DECIMAL BINARY (BCD) 95V 8 5V 7 5V 6 5V 5 5V 4 5V 3 5V 2 5V 1 5V 74147 I9 I8 I7 I6 I5 I4 I3 I2 I1 A0 A1 A2 A3 10 line to 4 line Encoder
- 15. 0 1 2 3 4 5 6 7 8 9 DECODER BINARY (BCD) DECIMAL 1 0V 20V 4 0V 8 0V 74LS42 A3 A2 A1 A0 9 8 7 6 5 4 3 2 1 0 4 line to 10 line Decoder
- 16. BCD-to- 7-Segment Decoder/ Driver DECODERS: BCD TO7-SEGMENT DECODER/DRIVER BCD input 0 0 0 0 Decimal output LED 0 0 0 10 0 1 00 0 1 10 1 0 0 • Electronic decoders are available in IC form. • This decoder translates from BCD to decimal. • Decimals are shown on an 7-segment LED display. • This IC also drives the 7-segment LED display.
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