1.  Design an 8-4-2-1 BCD code converter to drive a seven-segment indicator. The four inputs to the converter circuit (A, B, C, and D in Figure 8-15) represent an 8-4-2-1 binary-coded-decimal digit. Assume that only input combinations representing the digits 0 through 9 can occur as inputs so that the combinations 1010 through 1111 are don’t-cares. Design your circuit using only two-, three-, and four-input NAND gates and inverters. Try to minimize the number of gates required. The variables A, B, C, and D will be available from toggle switches.

 

Any solution that uses 18 or fewer gates and inverters (not counting the four inverters for the inputs) is acceptable.

2.  Work Design Problem 8.A using two-, three, and four input NOR gates and inverters instead of NAND gates and inverters. Any solution that uses 19 gates and inverters or fewer (not counting the four inverters for the inputs) is acceptable.

8.A Design an 8-4-2-1 BCD code converter to drive a seven-segment indicator. The four inputs to the converter circuit (A, B, C, and D in Figure 8-15) represent an 8-4-2-1 binary-coded-decimal digit. Assume that only input combinations representing the digits 0 through 9 can occur as inputs so that the combinations 1010 through 1111 are don’t-cares. Design your circuit using only two-, three-, and four-input NAND gates and inverters. Try to minimize the number of gates required. The variables A, B, C, and D will be available from toggle switches.

Any solution that uses 18 or fewer gates and inverters (not counting the four inverters for the inputs) is acceptable.

8.O Work Design Problem 8.A using two-, three, and four input NOR gates and inverters instead of NAND gates and inverters. Any solution that uses 19 gates and inverters or fewer (not counting the four inverters for the inputs) is acceptable.

Use b (not 5 ) for 6. Use 4 (not 4) for 9.