Brad Hill ELEC 7250 Logic Simulator 4252006 ELEC

Brad Hill ELEC 7250 Logic Simulator 4/25/2006 ELEC 7250: Hill 1

Simulation Table § Table created § Gate Name § Fan-in and Fan-out § Input and Output Array § Signal Array § Holds Signal Value during simulation § Set to 0 before each vector is applied 4/25/2006 ELEC 7250: Hill 2

Result Tables § Primary Input and Primary Arrays § Contains value of each Input Vectors and Expected Output Vectors § Simulated Circuit Table § Contains Input Vectors and Actual Output Vectors § Simulation Table § § § Gate Name Fan-in Fan-out § These Tables are Used to Determine if there is and error with specific input vectors 4/25/2006 ELEC 7250: Hill 3

Diagnosis § Back Track Incorrect Primary Outputs § Trace path to gate that produced Output § Suspected Gates and Signal List are formed § Primary Output is First Suspected Signal § The Gate that it originated from is the First Suspected Gate 4/25/2006 ELEC 7250: Hill 4

Diagnosis § Each Signal in the Suspected Signal List is traced to the gate it came from § Gates is added to Suspected Gate List § The Gates Fan-in is used to gather more signals for Suspected Signal List § Removing Primary Inputs if any § Keep Gate and Signal Lists for every incorrect output 4/25/2006 ELEC 7250: Hill 5

Diagnosis § It is likely that an Error in one gate will cause many invalid outputs § Each invalid output has its own Suspect list § The different lists can be compared with each other to find which Suspect Gate occurs the most § This Can Aid in Trying to Narrow the Faulty Gate Down 4/25/2006 ELEC 7250: Hill 6

Complexity § Depends on Complexity of Circuit § Number of Fan-outs of Gates § Number of Outputs § Number of Gates § Depth of Circuit § Increase in Any of these will result in an increase in execution time 4/25/2006 ELEC 7250: Hill 7

Conclusion § Work well with Errors in Gates that are reflected in many Outputs § Work well with Errors in Gates that are reflected in different Outputs given different Inputs § If there are not many Primary Outputs or Fanouts § Will only provide Possible Paths the Faulty Gate is in § May take considerable execution time with increasing numbers of Gates and Fan-outs 4/25/2006 ELEC 7250: Hill 8