Assembly Language Programming

Assignment #7

Sequential Circuits

1. A sequential circuit with two inputs (a and b) and one output is to be constructed to model the following situation. Prior to each clock pulse, the circuit is to output a 1 when both inputs are a 1 and on the previous clock pulse the inputs were a=1 and b=0. Start with a state diagram. Then decide how many JK flip flops would be needed. Decide how to encode the states and then build the excitation table. Also derive a truth table for the output circuit. Notice that the output depends on the current state and input values. Draw the completed circuit.

2. A counter circuit is to be designed to output a pair of values (a, b) in the following sequence. (0,0), (0,1), (1,1) and repeat. The counter advances with each clock pulse. There are no inputs. Use 2 JK flip-flops to implement the circuit. Show how the states are encoded and show your work in deriving the various functions.

3. Analyze the following sequential circuit. Give names to the possible states and draw a FSM that captures the functionality of the circuit. Note that the circuit has one input and one output. The gates are AND gates and the flip-flops are D-flip-flops.