Hi sir Ludovic, I'll like to implement a 4 bit counter using Alliance. The design I have uses Jk flipflops.. so I've been trying to implement a JK flipflop however, I always get an error when I get to apply the scmap command. I also get an error msg " driver conflict..." when I apply the "asimut -b jk jk r1" command. Here is my .vbe code. It gives no errors when compiled with asimut. My genpat code also gives no errors, however its when I want to simulate the behavioral description and synthesize the logic that I get stuck. -- code for a jk flip flop.. ENTITY jkt1 IS PORT( clock : IN BIT; j : IN BIT; k : IN BIT; q : OUT BIT; qbar : OUT BIT; vdd : IN BIT; vss : IN BIT ); END jkt1; Architecture jkflipflop of jkt1 is signal state : REG_BIT REGISTER Begin L1: BLOCK ((clock = '1') AND NOT(clock'STABLE) ) BEGIN state <= GUARDED NOT ((j = '1') AND (k = '1')); END BLOCK; L2: BLOCK ((clock = '1') AND NOT(clock'STABLE) ) BEGIN state <= GUARDED NOT ((j = '0') AND (k = '1')); END BLOCK; L3: BLOCK ((clock = '1') AND NOT(clock'STABLE) ) BEGIN state <= GUARDED ((j = '1') AND (k = '0')); END BLOCK; L4: BLOCK ((clock = '1') AND NOT(clock'STABLE) ) BEGIN state <= GUARDED ((j = '0') AND (k = '0')); END BLOCK; q <= state; qbar <= NOT state; End jkflipflop; Could you please help me on how to implement a flip flop. Thank you, John DB --------------------------------- Do You Yahoo!? Find a job, post your resume on Yahoo! Careers.