UNIVERSALITY OF NAND AND NOR GATES Objectives: To demonstrate the operation and characteristics of Universal logic gate. To construct the basic logic gates using universal logic gates. To apply universal logic gates in creating a logic circuit. Materials Needed: • 2 pcs IC - 7400 Quadruple 2 input NAND gates • 2 pcs IC - 7402 Quadruple 2 input NOR gates • 1 unit Digital Trainer Theory: All Boolean expressions consist of various combinations of the basic operation of OR, AND and INVERT. Therefore, any expres can be implemented using combinations of OR gates, AND gates and INVERTERS. It is possible however to implement any logic expression using only NAND gates and no other type of gate. This is because NAND gates, in the proper combination, can be used to perform each of the Boolean operations OR, AND and INVERT. This is illustrated in figure 3-1 below. x=A-A-A T A (a) INVERTER AB X = AB 2 T (b) AND ? x=AB=A+B ha ' A 3 B ??- (c) OR Figure 5-1: NAND Gates use to implement Boolean Functions In similar manner, it can be shown that NOR gates can be arranged to implement any of the Boolean operations. This is illustrated in figure 3-2 below. x=A+A -A 1 tal INVERTER AB 2 U ibi OR DD A.BAB 1 tel AND Figure 5-2: NOR Gates use to implement Boolean Functions Procedure: 1. Construct the circuit in figure 5-3 as shown below. SW 1 LED 1 Figure 5-3 2. Using logic switch Swi, apply the logic levels 0 and 1 to gate input (pin 1), in the sequence shown in the table 5-1. Record the output levels in the table 5-1. Table 5-1: NAND Gate Output S1 LED 1 0 1 3. Measure the voltage level of the output LED 1 for each value of the input. Write your observations on the space given. Voltage Level Input Binary 0 - Binary 1 - volts volts 4. Study your data in table 5-1. What logic function is being performed? 5. Connect the circuit found in figure 5-4. SW 1 AB LED 1 2 SW 2 Figure 5-4 6. Using logic switch Swi and Sw2, apply the logic levels 0 and 1 to gate input, in the sequence shown in the table 5-2. Record the output levels in the table 5-2. Table 5-2 SW1 SW2 LED 1 0 0 0 1 1 0 1 1 7. Study your data in table 5-2. What logic function is being performed? 8. Connect the circuit found in figure 5-5. SW 1 LED 1 SW 2 2 Figure 5-5 9. Using logic switch Sw1 and sw2, apply the logic levels 0 and 1 to gate input, in the sequence shown in the table 3-3. Record the output levels in the table 3-3. Table 5-3 SW1 SW2 LED 1 0 0 0 1 1 0 1 1 10. Study your data in table 5-3. What logic function is being performed? 11. Construct the circuit in figure 5-6 as shown below. SW 1 LED 1 Figure 5-6 12. Using logic switch SW1, apply the logic levels 0 and 1 to gate input (pin 1), in the sequence shown in the table 5-4. Record the output level the table 5-4. Table 5-4: NOR Gate Output 4/7 S1 LED 1 0 1 13. Study your data in table 5-4. What logic function is being performed? 14. Connect the circuit found in figure 5-7. SW 1 LED 1 2 SW 2 Figure 5-7 15. Using logic switch SW1 and SW2, apply the logic levels and 1 to gate input, in the sequence shown in the table 5-5. Record the output levels in the table 5-5. Table 5-5 SW1 SW2 LED 1 0 0 0 1 1 0 1 1 16. Study your data in table 5-5. What logic function is being performed? 17. Connect the circuit found in figure 5-8. SW 1 SW 2 LED 1 Figure 5-8 78. Using logic switch Swi and SW2, apply the logic levels and 1 to gate input, in the sequence shown in the table 5-6. Record the output levels in the table 5-6. Table 5-6 SW1 SW2 LED 1 0 0 0 1 1 0 1 1 5/ 9. Study your data in table 5-6. What logic function is being performed?
