LAB 008 4 bit adder and subtractor PDF

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EXPERIMENT - 14 4-BIT ADDER Objectives The objectives of this experiment 1. To study the IC 74LS83 4-bit Adder 2. To verify the operation of IC 74LS83 4-bit Adder. Equipment Required IC 74LS83 Multi-meter Cutter Single Core Wire Tweezers Pair of Pliers Theory IC type 7483 is a 4-bit binary parallel adder. It has two 4-bit inputs. Each input consists of 4-bits. The input A consists of A4 , A3 , A2 and A1 whereas input B consists of B4 , B3 , B2 and B1. It has four sum outputs consisting of S4 , S3 , S2 and S1. C0 is the input carry and C4 output carry. The Vcc is at pin 5 and GND is at pin 12. Diagram

Figure 1: Pin diagram of 73LS83 4-bit adder.

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Procedure 1. 2.

Connect the Digital Logic Trainer to 220V AC power supply Turn on the trainer and verify the voltage of the power supply using the multi-meter. It should be exactly +5V. Insert the IC 74LS83 on the trainer’s breadboard. Develop the circuit according to the figure 1. Connect A4 , A3 , A2 and A1 of input A to logic switches and mark them carefully. Connect B4 , B3 , B2 and B1 of input B to logic switches and mark them carefully. Connect carry in to ground. Connect S4 , S3 , S2 and S1 of output S to LEDs . Connect Carry out to the other LED and marks all outputs. Connect Vcc of all IC’s to the +5V available in the trainer. Connect GND of all IC’s to the ground available in the trainer. Now change the values of inputs A and B, and observe the output. .

3. 4. 5. 6. 7. 8. 9. 10. 11. 12.

Complete the table Complete the using the output of the circuit.

A4 0 1 1 1 0 0 0 1

A3 0 0 1 0 0 1 1 1

A2 0 0 0 0 1 1 0 1

Inputs A1 B4 0 0 0 1 0 1 1 0 1 0 1 0 0 0 1 1

B3 0 0 0 1 1 1 0 1

B2 0 0 1 1 0 1 1 1

B1

C4

S4

Outputs S3 S2

S1

0 0 0 1 1 1 1 1

Table 1: Observation table for 7483 4-bit adder In Case of Trouble 1. 2. 3.

Check the power supply Check the Vcc of all ICs. Check the GND of all ICs

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4. 5.

Check all the wire connections. Check the circuit wiring and remove all the breaks.

Conclusion

Exercise 1.

Make a connection diagram that employs two 4-bit adder to get the 8-bit adder.

2.

Develop a circuit that can act as a 4-bit adder-subtractor

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PRE-LAB-EXPERIMENT – 14

4-BIT ADDER

NOTE Obtain pin diagram of the IC required in the lab from lab staff. The IC data sheets are available in the lab. Consider 4-bit Adder and answer the following. Question No. 1: Write the names of input variables Inputs: Question No. 2: Write the names of output variables Outputs: S indicates the Sum an

Question No. 3: Draw the block diagram of 4-bit Adder

Question No. 4: Draw the pin diagram of the IC74LS83 4-bit adder. Diagram should show all inputs and outputs clearly.

Question No. 5: Complete the table

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A4 0 1 1 1 0 0 0 1

A3 0 0 1 0 0 1 1 1

A2 0 0 0 0 1 1 0 1

Inputs A1 B4 0 0 0 1 0 1 1 0 1 0 1 0 0 0 1 1

B3 0 0 0 1 1 1 0 1

B2 0 0 1 1 0 1 1 1

B1

C4

S4

Outputs S3 S2

S1

0 0 0 1 1 1 1 1

Question No. 6: Develop 4 –bit adder using full adders. Draw the block diagram.

Full Adder

Full Adder

Full Adder

Full Adder

Question No. 7: Develop 4 –bit adder – subtractor . Draw the logic diagram using 74LS83 .

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EXPERIMENT - 15

4-bit Binary Subtractor

Objectives The objectives of this experiment 1. To study the IC 74LS83 4-bit Subtractor 2. To verify the operation of IC 74LS83 4-bit Subtractor. Equipment Required IC 74LS83,74LS04 Multi-meter Cutter Single Core Wire Tweezers Pair of Pliers Theory As with the binary adder, we can also have 4-bit full binary subtractor connected or “cascaded” together to subtract two parallel 4-bit numbers from each other. The only difference between a full adder and a full subtractor is the inversion of one of the inputs. So by using an 4-bit adder and 4 number of inverters (NOT Gates), the process of subtraction becomes an addition as we can use two’s complement notation on all the bits in the subtrahend and setting the carry input of the least significant bit to a logic “1” (HIGH). Then we can use a 4-bit full-adder ICs such as the 74LS283 and 74LS04 to perform subtraction simply by using two’s complement on the subtrahend, B inputs as X – Y is the same as saying, X + (-Y) which equals X plus the two’s complement of Y. If we want to use the 4-bit adder for addition all we would need to do is set the carry-in (CIN) input LOW at logic “0”.

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Diagram

Procedure 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.

Connect the Digital Logic Trainer to 220V AC power supply Turn on the trainer and verify the voltage of the power supply using the multi-meter. It should be exactly +5V. Insert the IC 74LS83 and 74LS04 on the trainer’s breadboard. Develop the circuit according to the figure 1. Connect A4 , A3 , A2 and A1 of input A to logic switches and mark them carefully. Connect B4 , B3 , B2 and B1 of input B to Outputs of NOT gate IC and give input to NOT gate IC from logics switches marking them carefully. Connect carry in to +5V. Connect D4 , D3 , D2 and D1 of output D to LEDs . Connect Borrow out to the other LED and marks all outputs. Connect Vcc of all IC’s to the +5V available in the trainer. Connect GND of all IC’s to the ground available in the trainer. Now change the values of inputs A and B, and observe the output. .

Complete the table Complete the using the output of the circuit.

A4 0 1 1 1 0 0

A3 0 0 1 0 0 1

A2 0 0 0 0 1 1

Inputs A1 B4 0 0 0 1 0 1 1 0 1 0 1 0

B3 0 0 0 1 1 1

Logic Design and Switching Theory Lab

B2 0 0 1 1 0 1

B1

Bout

D4

Outputs D3 D2

D1

0 0 0 1 1 1

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0 1

1 1

0 1

0 1

0 1

0 1

1 1

1 1

In Case of Trouble 6. 7. 8. 9. 10.

Check the power supply Check the Vcc of all ICs. Check the GND of all ICs Check all the wire connections. Check the circuit wiring and remove all the breaks.

Conclusion

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