Dept. of ECE, CIT, Gubbi Page 1

Verification: 1) A.B = A + B 7404 7404 7404 A B A.B A.B 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 A B A B A + B 0 0 1 1 1 0 1 1 0 1 1 0 0 1 1 1 1 0 0 0 2) A+B = A. B 7404 7404 7404 A B A+B A+B 0 0 0 1 0 1 1 0 1 0 1 0 1 1 1 0 A B A B A. B 0 0 1 1 1 0 1 1 0 0 1 0 0 1 0 1 1 0 0 0 Dept. of ECE, CIT, Gubbi Page 1

Experiment No: 1(A) Date: Demorgan s Theorem for 2 variables Aim: To verify Demorgan s theorem for 2 variables Components required: IC 7404, 7432, 7408, Digital IC Trainer Kit, Patch cards Theory:- Theorem 1: The compliment of the product of two variables is equal to the sum of the compliment of each variable. Thus according to De-Morgan s laws or De-Morgan's theorem if A and B are the two variables or Boolean numbers. Then accordingly, A.B = A + B Theorem 2:- The compliment of the sum of two variables is equal to the product of the compliment of each variable. Thus according to De Morgan s theorem if A and B are the two variables then, A+B = A. B De-Morgan's laws can also be implemented in Boolean algebra in the following steps:- 1. While doing Boolean algebra at first replace the given operator. That is (+) is replaced with (.) and (.) is replaced with (+). 2. Compliment of each of the term is to be found. Procedure: 1. Realize the Demorgans theorem using logic gates. 2. Connect VCC and ground as shown in the pin diagram. 3. Make connections as per the logic gate diagram. 4. Apply the different combinations of input according to the truth tables. Verify that the results are correct. Dept. of ECE, CIT, Gubbi Page 2

Given problem: Truth table: Switching Expressions A B C D Y Y= f(a,b,c,d)=σm(5,6,7,13,14,15) 0 0 0 0 0 Y= f(a,b,c,d)=πm(0,1,2,3,4,8,9,10,11,12) 0 0 0 1 0 0 0 1 0 0 0 0 1 1 0 0 1 0 0 0 0 1 0 1 1 0 1 1 0 1 0 1 1 1 1 1 0 0 0 0 1 0 0 1 0 1 0 1 0 0 1 0 1 1 0 1 1 0 0 0 1 1 0 1 1 1 1 1 0 1 1 1 1 1 1 K-map Simplification: Dept. of ECE, CIT, Gubbi Page 3

Experiment No: 1(B) Sum of Product and Product of Sum Date: Aim: To design sum-of product and product-of-sum expressions using Basic gates and Universal gates. Components Required: IC 7408 (AND), IC 7404 (NOT), IC 7432 (OR), IC 7400 (NAND), IC 7402 (NOR), IC 7486 (EX-OR), IC Trainer Kit, Patch cards Theory: Canonical Forms (Normal Forms): Any Boolean function can be written in disjunctive normal form (sum of min-terms) or conjunctive normal form (product of max-terms). A Boolean function can be represented by a Karnaugh map in which each cell corresponds to two minterm. Sum of minterms : Sum Of Product (SOP) Product of maxterms : Product Of Sum (POS) Procedure: 1. Verify that the gates are working. 2. Construct a truth table for the given problem. 3. Draw a Karnaugh Map corresponding to the given truth table. 4. Simplify the given Boolean expression manually using the Karnaugh Map. A. Implementation Using Logic Gates: 5. Realize the simplified expression using logic gates. 6. Connect VCC and ground as shown in the pin diagram. 7. Make connections as per the logic gate diagram. 8. Apply the different combinations of input according to the truth tables. Verify that the results are correct. B. Implementation Using Universal Gates: 1. Convert the AND-OR logic into NAND-NAND and NOR-NOR logic. 2. Realize the simplified Boolean expressions using only NAND gates, and then using only NOR gates. 3. Connect the circuits according to the circuit diagrams, apply inputs according to the truth table and verify the results. Dept. of ECE, CIT, Gubbi Page 4

Simplified Boolean expression: (i) Simplification using Basic Gates: (ii) Simplification using NAND Gate: (iii) Simplification using NOR Gate: Dept. of ECE, CIT, Gubbi Page 5

Result: Exercise: An automobile alarm circuit is used to detect certain undesirable conditions. Three switches are used to indicate the status of the door by the driver s seat, the ignition, and the headlights respectively. Design the logic circuit with these three switches as inputs so that the alarm will be activated whenever either of the following conditions exists: The headlights are on while the ignition is off The door is open while ignition is on. Dept. of ECE, CIT, Gubbi Page 6

Digital Electronics Lab (15ECL38) 2017-18 1. Half Adder Truth Table: A B S C 0 0 0 0 0 1 1 0 1 0 1 0 1 1 0 1 S =A B C = A.B Realization of Half Adder: i). Using Basic gates ii). Using NAND gates Dept. of ECE, CIT, Gubbi Page 7

Experiment No: 2 Date: ADDERS AND SUBTRACTORS Aim: (i) To realize half/full adder using Logic gates & NAND gates (ii) To realize half/full Subtractor using Logic gates & NAND gates Components Required: IC 7408, IC 7432, IC 7486, IC 7404, IC 7400, Patch chords Theory: Half-Adder: A combinational logic circuit that performs the addition of two data bits, A and B, is called a half-adder. Addition will result in two output bits; one of which is the sum bit S, and the other is the carry bit, C. The Boolean functions describing the half-adder are: S =A B C = A.B Full-Adder: The half-adder does not take the carry bit from its previous stage into account. This carry bit from its previous stage is called carry-in bit. A combinational logic circuit that adds two data bits, A and B, and a carry-in bit, Cin, is called a full-adder. The Boolean functions describing the full-adder are: S = A B Cin C = A.B+ Cin (A B) Half Subtractor: Subtracting a single-bit binary value B from another A (i.e. A -B) produces a difference bit D and a borrow out bit Br. This operation is called half subtraction and the circuit to realize it is called a half subtractor. The Boolean functions describing the half-subtractor are: D =A B Br= A.B Full Subtractor: Subtracting two single-bit binary values, B, Cin from a single-bit value A produces a difference bit D and a borrow out Br bit. This is called full subtraction. The Boolean functions describing the fullsubtractor are: D = A B Cin Br= A.B + A.Cin + B.Cin Dept. of ECE, CIT, Gubbi Page 8

Digital Electronics Lab (15ECL38) 2017-18 2. Full Adder Truth Table: A B Cin S C 0 0 0 0 0 0 0 1 1 0 0 1 0 1 0 0 1 1 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 0 1 1 1 1 1 1 S = A B Cin C = A.B + Cin (A B) Realization of Full Adder: (i) using logic gates: (ii) using Nand gates: Dept. of ECE, CIT, Gubbi Page 9

Procedure: 1. Verify that the gates are working. 2. Make the connections as per the circuit diagram for the half adder circuit, on the trainer kit. 3. Switch on the VCC power supply and apply the various combinations of the inputs according to the respective truth tables. 4. Verify that the outputs are according to the expected results. 5. Repeat the procedure for the full adder circuit, the half subtractor and full subtractor circuits. 6. Verify that the sum/difference and carry/borrow bits are according to the expected values. Dept. of ECE, CIT, Gubbi Page 10

3. Half Subtractor Truth Table: A B D Br 0 0 0 0 0 1 1 1 1 0 1 0 1 1 0 0 D =A B Br = A.B Realization of Half Subtractor: (ii) (i) using logic gates ii)using Nand gates Dept. of ECE, CIT, Gubbi Page 11

4. Full Subtractor Truth Table: A B Cin D Br 0 0 0 0 0 0 0 1 1 1 0 1 0 1 1 0 1 1 0 1 1 0 0 1 0 1 0 1 0 0 1 1 0 0 0 1 1 1 1 1 D = A B Cin Br= A.B + A.Cin + B.Cin Realization of Full Subtractor: (i) Using logic gates: (ii) Using Nand gates Result: Dept. of ECE, CIT, Gubbi Page 12

Digital Electronics Lab (15ECL38) 2017-18 1. 4-BIT BINARY ADDER Example: 7+2=09 which is equal to (1001)2 7 is realized at A3 A2 A1 A0 = 0111 2 is realized at B3 B2 B1 B0 = 0010 Sum = (1001)2 Circuit: MSB LSB INPUTS Cin A3 A2 A1 A0 B3 B2 B1 B0 OUTPUT Cout S3 S2 S1 S0 Dept. of ECE, CIT, Gubbi Page 13

Digital Electronics Lab (15ECL38) 2017-18 Experiment No: 3 Date: PARALLEL ADDER AND SUBTRACTOR USING 7483 Aim: To design and set up the following circuit using IC 7483. i) A 4-bit binary parallel adder. ii) A 4-bit binary parallel subtractor. Components Required: IC 7483, IC 7486, etc. Theory: The Full adder can add single-digit binary numbers and carries. The largest sum that can be obtained using a full adder is (11)2. Parallel adders can add multiple-digit numbers. If full adders are placed in parallel, we can add two- or four-digit numbers or any other size desired. Figure below uses STANDARD SYMBOLS to show a parallel adder capable of adding two digit binary numbers. The addend would be input on the A inputs (A2 = MSD, A1 = LSD), and the augend input on the B inputs (B2 = MSD, B1 = LSD). To add four bits need four full adders arranged in parallel. IC 7483 is a 4- bit parallel adder is used. Procedure for Adding two 4-Bit data: 1. Check all the components for their working. 2. Insert the appropriate IC into the IC base. 3. Make connections as shown in the circuit diagram. 4. Apply augend and addend bits on A and B and cin=0. 5. Verify the results and observe the output of ADDER CIRCUIT Dept. of ECE, CIT, Gubbi Page 14

Digital Electronics Lab (15ECL38) 2017-18 2. 4-Bit Binary Subtractor. (i) 4 bit subtraction operation using 7483 for A>B and Cin=1 Example: 8 3 = 5 which is equal to (0101)2 8 is realized at A3 A2 A1 A0 = 1000 3 is realized at B3 B2 B1 B0 through X-OR gates = 0011 Output of X-OR gate is 1 s complement 2 s Complement can be obtained by adding Cin = = 1100 1 Therefore Cin = 1 A3 A2 A1 A0 = 1 0 0 0 B3 B2 B1 B0 = 1 1 0 0 S3 S2 S1 S0 = 0 1 0 1 Cout = 1 (Ignored) (ii) 4 bit subtraction operation using 7483 for A<B and Cin=1 Example: 14 15 = -1 (1111)2 14 is realized at A3 A2 A1 A0 = 1110 15 is realized at B3 B2 B1 B0 through X-OR gates = 1111 Output of X-OR gate is 1 s complement of 15 = 0000 2 s Complement can be obtained by adding Cin = 1 Therefore Cin = 1 A3 A2 A1 A0 = 1 1 1 0 B3 B2 B1 B0 = 0 0 0 0 S3 S2 S1 S0 = 1 1 1 1 since the most significant bit of the result is 1, this is a negative number, so form the two's complement of (1111)=-(0001) 2 Circuit: Dept. of ECE, CIT, Gubbi Page 15

Procedure for subtracting two 4-Bit data: 1. Check all the components for their working. 2. Insert the appropriate IC into the IC base. 3. Make connections as shown in the circuit diagram. 4. Apply Minuend and subtrahend bits on A and B and cin=1. 5. Verify the results and observe the outputs. Result: Dept. of ECE, CIT, Gubbi Page 16

Digital Electronics Lab (15ECL38) 2017-18 4-BIT COMPARATOR: Truth Table: A3 A2 A1 0 0 0 0 1 0 1 0 1 0 0 1 0 1 0 1 1 0 0 1 1 1 1 1 A0 B3 B2 B1 B0 A>B A<B 0 0 0 0 1 0 1 1 0 0 1 1 1 0 0 1 0 1 0 0 0 1 0 1 1 0 0 1 0 1 0 0 0 0 1 1 1 0 1 1 1 0 0 0 1 1 0 0 0 1 1 1 1 0 1 0 A=B 0 0 1 0 0 0 1 0 IC 7485 Dept. of ECE, CIT, Gubbi Page 17

Experiment No: 4 Date: COMPARATORS Aim: To realize One & Two Bit Comparator and study of 7485 magnitude comparator. Components required: IC 7485, Patch Cards & IC Trainer Kit. Theory: Magnitude Comparator is a logical circuit, which compares two signals A and B and generates three logical outputs, whether A > B, A = B, or A < B. IC 7485 is a high speed 4-bit Magnitude comparator, which compares two 4-bit words. The A = B Input must be held high for proper compare operation. Result: Exercise A simple security system for two doors consists of a card reader and a keypad. A person may open a particular door if he or she has a card containing the corresponding code and enters an authorized code for that card. The output from the card reader are as follows. Action A B No card inserted 0 0 Valid Code for Door 1 0 1 Valid Code for Door2 1 1 Invalid card code 1 0 To unlock a door, a person must hold down the proper keys on the keypad and then insert the card in the reader. The authorized keypad codes for door 1 are 101 and 110, and the authorized keypad codes for door 2 are 101 and 011. If the card has an invalid code or if the wrong keypad code is entered, the alarm will ring when card is inserted. If the correct keypad code is entered, the corresponding door will be unlocked when the card is inserted. Dept. of ECE, CIT, Gubbi Page 18

Digital Electronics Lab (15ECL38) 2017-18 A. 4:1 MULTIPLEXER Output Y= E S1 S0 I0 + E S1 S0I1 + E S1S0 I2 + E S1S0I3 Truth Table: Select Lines Output S1 0 0 1 1 S0 0 1 0 1 Y I0 I1 I2 I3 Dept. of ECE, CIT, Gubbi Page 19

Experiment No: 5(a) Date: 4:1 MULTIPLEXER USING GATES Aim: To design and set up a 4:1 Multiplexer (MUX) using gates. Components Required: IC 74153, IC 7404, 7432, 7411 and Patch Cords & IC Trainer Kit. Theory: Multiplexers are very useful components in digital systems. They transfer a large number of information units over a smaller number of channels, (usually one channel) under the control of selection signals. Multiplexer means many to one. A multiplexer is a circuit with many inputs but only one output. By using control signals (select lines) we can select any input to the output. Multiplexer is also called as data selector because the output bit depends on the input data bit that is selected. The general multiplexer circuit has 2n input signals, n control/select signals and 1 output signal. Procedure: 1. The connection is made as shown in the diagram. 2. Here, S1 and S0 are the channel selection lines, I0, I1, I2, I3 are the respective data lines of the channels and Y is the output. 3. Based on the selection lines one of the inputs will be selected at the output, and thus the truth table is verified. Dept. of ECE, CIT, Gubbi Page 20

Digital Electronics Lab (15ECL38) 2017-18 B. 3 Variable function using IC 74151 Truth table: Select Lines Output C 0 0 0 0 1 1 1 1 B A Y 0 0 0 0 1 1 1 0 1 1 1 0 0 0 0 0 1 0 1 0 0 1 1 1 Dept. of ECE, CIT, Gubbi Page 21

Experiment No: 5(b) Date: 8:1 MULTIPLEXER USING 74151 Aim: To design and set up the following circuit 3 variable function using IC 74151 (8:1 MUX) Components Required: IC 74151, Patch Cords & IC Trainer Kit. Procedure: 1. For the given expression, a truth table is to be written. 2. An expression in SOP format is to be written. 3. The connection is made according to the obtained expression. 4. The truth table is verified for that particular expression. Result: Dept. of ECE, CIT, Gubbi Page 22

Digital Electronics Lab (15ECL38) 2017-18 1:8 De-mux and 3:8 Decoder using IC 74138 Truth table: Select Lines Output C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 G1 1 1 1 1 1 0 0 1 1 G1 1 1 1 1 0 1 0 1 1 G1 1 1 1 0 1 1 1 1 1 G1 1 1 1 0 0 1 1 1 1 G1 1 1 0 1 1 1 1 1 1 G1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 G1 1 1 G1 Dept. of ECE, CIT, Gubbi Page 23

Experiment No: 6 Date: 1:8 DEMUX AND 3:8 DECODER USING IC 74138 Aim: To design 1:8 Demux and 3:8 Decoder using IC 74138 Components Required: IC 74138, Patch Cords & IC Trainer Kit. Theory: A demultiplexer (or demux) is a device that takes a single input line and routes it to one of several digital output lines. A demultiplexer of 2 n outputs has n select lines, which are used to select which output line to send the input. A demultiplexer is also called a data distributor. A decoder is a circuit which has n inputs and 2 n outputs, and outputs 1 on the wire corresponding to the binary number represented by the inputs. A standard decoder typically has an additional input called Enable. Output is only generated when the Enable input is activated. Procedure (1:8 Demux): 1. The pins indicated as A, B and C are the selection lines, G1 acts as an input line, Y0 to Y7 are the output channels. 2. A particular channel can be selected by choosing the proper bits for A, B and C lines. 3. As IC 74138 is having active low outputs, initially all the outputs will be high 4. Based on the bit given to G1 after selecting the channel, the same bit will be reflected in that particular channel. 5. The truth table is verified for different combination of bits on both selection lines and input G1. NOTE: HERE PIN E1 = G1 AND PINS E2 AND E3 SHOULD BE CONNECTED TO GROUND Dept. of ECE, CIT, Gubbi Page 24

Digital Electronics Lab (15ECL38) 2017-18 E1 E3 Truth table: Enable Select Lines Output E3 E2 E1 C B A Y0 Y1 Y2 Y3 Y4 1 X X X X X 1 1 1 1 1 X 1 X X X X 1 1 1 1 1 X X 0 X X X 1 1 1 1 1 Y5 Y6 Y7 1 1 1 1 1 1 1 1 1 0 0 1 0 0 0 0 1 1 1 1 0 0 1 0 0 1 1 0 1 1 1 0 0 1 0 1 0 1 1 0 1 1 0 0 1 0 1 1 1 1 1 0 1 0 0 1 1 0 0 1 1 1 1 0 0 0 1 1 0 1 1 1 1 1 1 0 0 1 1 1 0 1 1 1 1 1 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 0 1 1 1 0 Dept. of ECE, CIT, Gubbi Page 25

Procedure (3:8 DECODER): 1. The connections are made as shown in the diagram 2. Enable pins are used to enable the IC 3. Using Select inputs, a particular output is selected. 4. Since IC 74138 is having an active low output, the particular line will give a digital low. Result: Dept. of ECE, CIT, Gubbi Page 26

Digital Electronics Lab (15ECL38) 2017-18 1. SR FLIPFLOP: Truth table: Clk S R Q Q States X 0 0 Q Q No Change 0 0 Q Q No Change 0 1 0 1 Reset 1 0 1 0 Set 1 1 - - Invalid Dept. of ECE, CIT, Gubbi Page 27

Experiment No: 7 Date: FLIP FLOPS Aim: To realize the following Flip-flops using NAND gates: A. Clocked SR Flip-flop B. JK Flip-flop Components required: IC 7410, IC7400 Theory: A flip-flop is a circuit that has two stable states and can be used to store state information. A flip-flop is a bistable multivibrator. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs. It is the basic storage element in sequential logic. Flip-flops and latches are a fundamental building block of digital electronics systems used in computers, communications, and many other types of systems. A flip flop is a bit bucket ; it holds a single binary bit.flip flops are actually an application of logic gates. With the help of Boolean logic we can create memory with them. Flip flops can also be considered as the most basic idea of a Random Access Memory [RAM]. The most commonly used application of flip flops is in the implementation of a feedback circuit. As a memory relies on the feedback concept, flip flops can be used to design it. Procedure: 1. Make the connections as shown in the circuit diagrams. 2. Apply inputs as shown in the truth tables, 3. Check the outputs of the circuits; verify that they match wit5h the truth tables. Dept. of ECE, CIT, Gubbi Page 28

2. JK FLIPFLOP: Clk J K Q Q States X 0 0 Q Q No Change 0 0 Q Q No Change 0 1 0 1 Reset 1 0 1 0 Set 1 1 Q Q Toggle Dept. of ECE, CIT, Gubbi Page 29

Result: Dept. of ECE, CIT, Gubbi Page 30

Digital Electronics Lab (15ECL38) 2017-18 1. SERIAL INPUT SERIAL OUTPUT (SISO): Truth Table: CLK 1 2 3 4 5 6 7 Serial I/P Q3 Q2 Q1 Q0 D0=0 0 X X X D1=1 1 0 X X D2=1 1 1 0 X D3=1 1 1 1 0=D0 X X 1 1 1=D1 X X X 1 1=D2 X X X X 1=D3 Dept. of ECE, CIT, Gubbi Page 31

Experiment No: 8 Date: SHIFT REGISTERS Aim: To study IC 7474, and the realization of SIPO, SISO, PISO, PIPO operations using the same. Components required: IC 7474, patch cards etc. Theory: A shift register is a group of flip-flops (typically 4 or 8) that are arranged so that the values stored in the flip-flops are shifted from one flip-flop to the next for every clock. Shift registers are used extensively in logic circuits to control digital displays. A classic example is numbers being typed into a calculator. As the numbers are entered, the digits shift to the left one position. This shifting is controlled by a shift register. 1. SERIAL INPUT SERIAL OUTPUT (SISO): Procedure: 1. Connections are made as shown in the SISO circuit diagram. 2. The shift register is loaded with 4 bits of data one by one serially. 3. At the end of the 4 th clock pulse, the first data d0 appears at Q0. 4. Applying another clock pulse will push the second data bit, d1 to Q0. 5. Applying yet another clock pulse gives the third data bit, d2 at Q0, and so on. Dept. of ECE, CIT, Gubbi Page 32

2. SERIAL INPUT PARALLEL OUTPUT (SIPO): Truth Table: CLK Serial I/P Q3 Q2 Q1 Q0 1 1 1 X X X 2 0 0 1 X X 3 1 1 0 1 X 4 1 1 1 0 1 3. PARALLEL INPUT PARALLEL OUTPUT (PIPO): Truth Table: Parallel I/P Parallel O/P CLK D3 D2 D1 D0 Q3 Q2 Q1 Q0 1 1 0 1 1 1 0 1 1 Dept. of ECE, CIT, Gubbi Page 33

2. SERIAL INPUT PARALLEL OUTPUT (SIPO): Procedure: 1. Connections are made as shown in the SIPO circuit diagram. 2. On applying the first bit of data and then a clock pulse, it can be observed that this data appears at (Q3). 3. Now, applying the second bit of data and a clock pulse, the bit at Q3 shifts to Q2 and Q3 will be loaded with the new data. 4. This repeats until all 4 data bits are loaded. 5. At the end of the 4th clock pulse, all 4 bits are available at the parallel output pins Q3 through Q0. 3. PARALLEL INPUT PARALLEL OUTPUT (PIPO): Procedure: 1. Connections are made as shown in the PIPO mode circuit diagram. 2. Apply the 4 data bits as input to D3, D2, D1, D0. 3. Apply one clock pulse 4. Note that the 4 bit data at parallel inputs appears at the parallel output pins Q3, Q2, Q1, Q0 respectively. Dept. of ECE, CIT, Gubbi Page 34

4. PARALLEL INPUT SERIAL OUTPUT (PISO): D3 D2 D1 D0 Q0 Truth Table: Mode Clock Parallel I/P O/P M CLK D3 D2 D1 D0 Q3 Q2 Q1 Q0 1 1 1 0 1 1 1 0 1 1 0 2 0 0 0 0 X 1 0 1 0 3 0 0 0 0 X X 1 0 0 4 0 0 0 0 X X X 1 Dept. of ECE, CIT, Gubbi Page 35

4. PARALLEL INPUT SERIAL OUTPUT (PISO): Procedure: 1. Connections are made as shown in the PISO circuit diagram. 2. Apply the 4-bit data at the parallel I/P pins D3, D2, D1, D0 and apply single clock pulse to load the data to all 4 registers. 3. Now make all data bits as 0 and apply clock pulse one by one to get the data bit by bit at the output line. 4. The data applied at the parallel input pins will shift and comes out serially at the output line Q0. NOTE: Here there is no Mode M pin. It just indicates the status of loading the data and shifting the data. M 1 indicates data loading operation. M -- 0 indicates shifting operation. Result: Exercise: A shifter is a combinational network capable of shifting of 0 s and 1 s to the left or right, leaving vacancies, by a fixed number of places as a result of control signal. For example, assuming vacated positions are replaced by 0 s, the string 0011 when shifted right by 1 bit position becomes 0001 and when shifted left by 1 bit position becomes 0110. A shifter to handle an n bit string can be readily designed with n multiplexers. Bits from the string are applied to the data input lines. The control signals for the various actions are applied to the select input lines. The shifted string appears on the output lines. Design a shifter for handling a 4 bit string where table indicates the control signals and desired actions. Vacated positions should be filled with 0 s. S1 S0 Action 0 0 No change 0 1 Shift right 1 bit position 1 0 Shift left 1 bit position 1 1 Clear data Dept. of ECE, CIT, Gubbi Page 36

1. RING Counter: Truth table CLK QA QB QC QD 1 1 0 0 0 2 0 1 0 0 3 0 0 1 0 4 0 0 0 1 5 1 0 0 0 6 0 1 0 0 Dept. of ECE, CIT, Gubbi Page 37

Experiment No: 9 Date: RING & JHONSON COUNTER USING IC 7476 Aim: To design and study the operation of a ring counter and a Johnson Counter. Components required: IC 7476, Patch Cards & IC Trainer Kit. Theory: A ring counter is a circular shift register which is initiated such that only one of its flip-flops is the state one while others are in their zero states. A ring counter is a Shift Register with the output of the last one connected to the input of the first, that is, in a ring. Typically, a pattern consisting of a single bit is circulated so the state repeats every n clock cycles if n flip-flops are used. It can be used as a cycle counter of n states. A Johnson counter (or switchtail ring counter, twisted-ring counter, walking-ring counter, or Moebius counter) is a modified ring counter, where the output from the last stage is inverted and fed back as input to the first stage. The register cycles through a sequence of bit-patterns, whose length is equal to twice the length of the shift register, continuing indefinitely. These counters find specialist applications, including those similar to the decade counter, digital-to-analog conversion, etc. They can be implemented easily using D- or JK-type flip-flops. Procedure: 1. Make the connections as shown in the respective circuit diagram. 2. Initial condition is set by setting up the circuit as shown in the figure. 3. There after all Pr and Clr pins of all F/Fs should be connected to VCC. 4. Apply clock and observe the output after each clock pulse, record the observations and verify that they match the expected outputs from the truth table. 5. Repeat the same procedure as above for the Johnson Counter circuit and verify its operation Dept. of ECE, CIT, Gubbi Page 38

Digital Electronics Lab (15ECL38) 2017-18 2. JHONSON Counter: Truth table CLK 1 2 3 4 5 6 7 8 9 10 QA QB QC 1 0 0 1 1 0 1 1 1 1 1 1 0 1 1 0 0 1 0 0 0 0 0 0 1 0 0 1 1 0 QD 0 0 0 1 1 1 1 0 0 0 Dept. of ECE, CIT, Gubbi Page 39

Result: Dept. of ECE, CIT, Gubbi Page 40

Digital Electronics Lab (15ECL38) 2017-18 1. MOD 10 Counter: Truth Table: Circuit diagram: CLK QD QC QB 0 0 0 0 1 0 0 0 2 0 0 1 3 0 0 1 4 0 1 0 5 0 1 0 6 0 1 1 7 0 1 1 8 1 0 0 9 1 0 0 Waveforms: QA 0 1 0 1 0 1 0 1 0 1 2. MOD 8 Counter: Truth Table: Circuit diagram: CLK QD QC QB QA 0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 Dept. of ECE, CIT, Gubbi Page 41

Experiment No: 10 Date: DECADE COUNTERS Aim: To rig up Mod N counter using IC 7490. Components required: IC7490,Patch cards, trainer kit,etc. Procedure: 1. Check all the components for their working. 2. Make connections as shown in the circuit diagram. 3. Clock pulses are applied one by one at the clock input and output is observed at QA,QB,QC and QD 4. Verify the Truth Table and observe the outputs. Result: Dept. of ECE, CIT, Gubbi Page 42

Circuit Diagram: Simulation of Full Adder Truth Table: A B Cin S C 0 0 0 0 0 0 0 1 1 0 S = A B Cin 0 1 0 1 0 0 1 1 0 1 C = A.B + Cin (A B) 1 0 0 1 0 1 0 1 0 1 1 1 0 0 1 1 1 1 1 1 Dept. of ECE, CIT, Gubbi Page 43

Experiment No: 11 Date: FULL ADDER USING SIMULATION TOOL Aim: To rig up a full adder circuit using basic gates Procedure to enter schematic and to simulate: 1. Switch on the computer and open the simulation software. 2. Select new file to draw the circuit diagram 3. Select the required components to the circuits from the library and place them on the window in required position 4. Wire the circuit according to the circuit diagram. 5. Connect the power supply and ground. 6. Save the circuit diagram with file name. 7. Click on simulation button and observe the led on and off condition and compare with truth table. Result: Dept. of ECE, CIT, Gubbi Page 44

Digital Electronics Lab (15ECL38) 2017-18 Circuit Diagram: Truth Table: CLK UP COUNTER DOWN COUNTER QC QB QA QC QB QA 0 0 0 0 1 1 1 1 0 0 1 1 1 0 2 0 1 0 1 0 1 3 0 1 1 1 0 0 4 1 0 0 0 1 1 5 1 0 1 0 1 0 6 1 1 0 0 0 1 7 1 1 1 0 0 0 Dept. of ECE, CIT, Gubbi Page 45

Experiment No: 12 Date: MOD 8 SYNCHRONOUS UP/DOWN COUNTER USING SIMULATION TOOL Aim: To rig up mod 8 synchronous up/down counter using simulation tool Procedure to enter schematic and to simulate: 1. Switch on the computer and select Simulation and software. 2. Select new file to draw the circuit diagram 3. Select the required components to the circuits from the library and place them on the window in required position 4. Wire the circuit according to the circuit diagram. 5. Connect the power supply, clock and ground. 6. Save the circuit diagram with file name. 7. Click on simulation button and observe the led on and off condition and compare with truth table. Result: Dept. of ECE, CIT, Gubbi Page 46

IC PIN DETAILS Dept. of ECE, CIT, Gubbi Page 47

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Dept. of ECE, CIT, Gubbi Page 49

Dept. of ECE, CIT, Gubbi Page 50

VIVA QUESTIONS 1. What are Analog Systems? Give Examples. 2. What are Digital Systems? Give Examples. 3. Mention the disadvantages of Analog systems over Digital systems. 4. Explain Boolean algebra. 5. State Principle of Duality. 6. State De morgan s Law. 7. Define Positive Logic and Negative Logic. 8. Define Literal. 9. Define MINTERM and MAX TERM. 10. Define a complementary function. 11. Explain Shannon s reduction theorem. 12. Which are the basic gates and universal gates. 13. Define combinational network with example. 14. Define Sequential Network with example. 15. Define Double-Rail and Single -Rail logic. 16. When a Boolean Expression is called completely specified? 17. Explain the significance of a Don t care function. 18. Explain the criteria of minimality. 19. Define implies, Subsumes, implicants. 20. What are Prime Implicants? 21. What is irredundant disjunctive normal formula? 22. What is an implicate? 23. What is a Map? Dept. of ECE, CIT, Gubbi Page 51

24. Explain the significance of Map. 25. What is a Minimal Sum and Minimal product? 26. Explain Quine - McClusky method. 27. Explain VEM method of reduction. 28. Explain Binary Adder and Subtractor. 29. Explain various scales of integration. 30. Define Carry Look Ahead Adder. 31. Define Comparator, Decoder and Encoder. 32. Give an example for Min-term generator. 33. Give an example for Max-term generator. 34. Define priority encoder. 35. Explain Multiplexing action. 36. Define PAL, PLA and PROM. 37. Differentiate between ROM and RAM. 38. What is a Memory? 39. What is internal state and secondary state? 40. Define Flip Flop and Latch. 41. Explain Basic Bi-stable element. 42. What is a metastable state? 43. Define setting and clearing in terms of flip-flop. 44. Explain SR Latch and Give an application. 45. Explain gated SR Latch and gated D Latch. 46. Explain Timing Diagram. 47. Explain Propagation Delay in gates. 48. Explain Set and Hold time in latches. Dept. of ECE, CIT, Gubbi Page 52

49. Explain Master-Slave Flip-Flop. 50. Explain the significance of edge-triggering. 51. Explain Data Lock Out. 52. Give the characteristic equations of JK, D and T Flip Flops. 53. Define Registers with example. 54. Define Counters with example. 55. Explain ripple, asynchronous and synchronous counters. 56. Explain Race Around Condition. 57. List the basic logic series. 58. Explain Semiconductor diode behavior. 59. What is Saturating Logic? 60. Explain Fan-Out and Fan-in in gates. 61. Explain DTL and TTL. 62. What is wired logic? 63. What is Totem pole Output? 64. Explain Schottky TTL. 65. Explain Emitter-Coupled Logic. 66. Which is the fastest of all the logic families? 67. What is a MOSFET? 68. Explain Enhancement and Depletion Mode in MOSFET s. 69. Explain Threshold voltage. 70. Explain MOSFET as Resistor. 71. Clearly differentiate between PMOS and NMOS Logic. 72. Explain CMOS Logic. 73. State Moore s Law. Dept. of ECE, CIT, Gubbi Page 53

74. Differentiate between Moore and Mealy Law. 75. Define FPGA. 76. Define PLD. 77. Define CPLD. 78. Define Simulation. 79. State the application of Sequence Generator. Dept. of ECE, CIT, Gubbi Page 54

Question Bank 1. Simplify and realize Demorgan s theorem for 2 variables. 2. Simplify and realize the given Boolean Expression using Universal Gates and verify the truth table. (Two expressions to be given). 3. Realize and verify the truth table of full adder basic gates only. 4. Realize and verify the truth table of a full Subtractor using basic gates only. 5. Conduct a suitable experiment on 7483 IC to realize the following operation on the given 4 bit data addition and subtraction. 6. Realize and verify 4 bit magnitude comparator using IC 7485 7. Realize 4:1 Multiplexer using gates only 8. Realize 3-Variable function using IC 74151(8:1 MUX) 9. Realize and verify 1:8 DEMUX and 3:8 decoder using IC 74138 10. Realize and verify the truth Table of JK Flip Flop using NAND gates 11. Realize and verify the truth Table of Clocked SR Flip Flop using NAND gates 12. Realize and verify Ring counter using IC 7476 13. Realize and verify Johnson counter using IC 7476 14. Realize a Modulo N counter using 7490, Write down the expected functional table and verify its truth table and also display the waveform. 15. Use IC 7474 Shift registers to display the following operations a) SIPO b) PIPO 16. Use IC 7474 Shift registers to display the following operations a) PISO b) SISO 17. Simulate full adder using simulation tool 18. Simulate MOD 8 Synchronous up / down counter using simulation tool ----------------------------------*****------------------------------ Dept. of ECE, CIT, Gubbi Page 55