UMBC CMSC 313, Computer Organization & Assembly Language, Fall 2002, Section 0101

More Finite State Machine Design

Tuesday 12/03, 2002

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Assigned Reading in Murdocca & Heuring:   

Assigned Reading in Neveln:   

Assigned:  DigSim3

Due:  HW5

Topics Covered:

• We took our good friend the sequence detector through the three steps of state reduction, state assignment and flip-flop selection.
• Our textbook gives the circuitry for the sequence detector after reducing the 7-state machine to a 6-state machine. However, the simplified SOP formulas obtained from the 6-state machine is actually worse than those we obtained from the 7-state machine. We changed the state assignment for the 6-state machine and obtained simplified SOP/POS formulas (using Karnaugh maps) that were better than the ones from the 7-state machine.
• Finally, we considered using J-K flip-flops instead of D flip-flops to implement the finite state machine for the sequence detector. We used the excitation table for J-K flip-flops and Karnaugh maps to obtain simplified Boolean formulas for the inputs to the J-K flip-flops. The resulting formulas were slightly simpler than the ones for D flip-flops.

Circuits in DigSim:

Following these links will launch the DigSim Java applet and load the circuit described.

• A Sequence Detector using J-K flip-flops