Exercises 5.

Q1. Design a modulo-4 up-down counter. (use D,FF)

Q2. Design a sequential circuit that detects an input sequence of 1011. The sequenc es may overlap. (A 1011 sequence detector gives an output of 1 when the input completes a sequence of 1011). (Use D, FF).

Q3. Derive the state diagram for an odd parity checker. The input arrives on a single line, X, one bit at a time. The circuit should produce an output of 1 if the number of 1's in the input sequence of four bits is odd. The circuit should reset to the starting state every four bits on the input.

Q4. Design the circuit for a soft drink machine. Each drink costs 30 c. The machine accepts quarters, dimes, and nickels. Assume that a coin sorter that accepts the coins and produces three signals, one corresponding to each of the three coins, is avail able. Assume that the signal on the coin sorter are separated far enough apart to en able other circuits to make a state transition between the pulses on any two of these lines. The sequential circuit should generate signals to release the soft drink bottle and the correct change. The coin sorter releases the appropriate coin when it re ceives a coin release signal. Use D, FF.

Q5. Design a 3 bit shift register. Use D,FF.