Question 9.PE.7: To investigate the full adder For this exercise you will nee...
To investigate the full adder
For this exercise you will need the following components and equipment:
1 – 74LS283 ic (4-bit binary full-adder)
1 – +5 V dc power supply
5 – LED (5 mm) and resistor (270 Ω)
Procedure (a)
1 Connect up the circuit shown in Figure 9.38. The pin connection diagram for the 74283 ic is shown in Figure 9.39.
Notice that, for this first part of the exercise, all four A inputs are connected together, as are all the four B inputs. With this arrangement, the addition is merely of two binary numbers
2 Apply the appropriate logic levels to inputs A and B respectively in order to verify the rules of binary addition given above.
Procedure (b)
1 The previous circuit should now be modified to that shown in Figure 9.40.
2 It will probably be more convenient if one input word (say, A) is left set up and the addition performed by setting the other as required. Thus.
3 Set input A_0A_1A_2A_3 to 0101 (decimal 5) and let this remain for the duration of this part of the exercise.
4 Set input B_0B_1B_2B_3 to the levels shown in parts (a) to (e) of Figure 9.41. Obtain the answers practically and theoretically, checking that the binary output agrees with its decimal equivalent.
