Sample Test 3 C421 Spring 2003  Name ________________________

Closed Book, Closed Notes, Closed Neighbor, Closed Computer, 1 8.5 x 11” crib sheet

25 points per problem                                                                                                                                               

1. Design a three-bit up/down counter. You should have a one bit input that specifies whether to count up or down. Implement your function with D-Flip Flops

2. Convert a T-type Flip-Flop to a:

a. D-Type Flip-Flop

b. R/S Flip-Flop

c. J/K Flip-Flop

3. Design a state machine that examines a serial input stream of bits and outputs a 1 if the sequence 0011 or 1101 is detected. The output should be 0 otherwise. Your input is one bit and your output is one bit. You should only examine groups of 4 bits.

4. Implement a circuit that counts from 4 to 11 (only!) by using a 74161 or 74163 and as little additional logic as possible. Also implement this via VHDL code as a state machine.