Tutorial by Examples

wire d = 1'bx; // say from previous block. Will be 1 or 0 in hardware if (d == 1'b) // false in simulation. May be true of false in hardware

wire a; wire b; reg q; always @(a) // b missing from sensativity list q = a & b; // In simulation q will change only when a changes In hardware, q will change whenever a or b changes.