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Step of 3 7.28DP The ABEL program for combination lock machine state table is as follows. module CLM title 'Combination-lock machine' "Input and Output pins Clk,X pin; Q1,Q2,Q3 pin istype 'reg'; Unlk,Hint pin istype 'com'; "Definitions S=[Q1,Q2,Q3]; "state variables A=[0,0,0]; "state encoding B=[0,0,1]; C=[0,1,0]; E=[1,0,0]; F=[1,0,1]; G=[1,1,0]; H=[1,1,1]; State_diagram S "state defining State A: if X==0 then B with Hint=1} else A with Hint=0} State B: if X==0 then B with Hint=0} else C with Hint=1} State C: if X==0 then B with {Unlk=0; Hint=0} else D with {Unlk=0; Hint=1} State D: if X==0 then E with Hint=1} else A with Hint=0} State E: if X==0 then B with Hint=0} else F with {Unlk=0; Hint=1} State F: if X==0 then B with Hint=0} else G with Hint=1} State G: if X==0 then E with {Unlk=0; Hint=0} else H with {Unlk=0; Hint=1} State H: if X==0 then B with Hint=1} else A with Hint=0} equations S.CLK Clk; end CLM Step of 3 The test vector for the Combination lock state machine is as follows. test_vectors [S, Hint Step of 3 The timing diagram for combination-lock state machine is as shown in Figure 1. CLK Q2 Q3 UNLK HINT Figure 1: The timing diagram for combination lock state machine.