The thermodynamics of concentrated, semiflexible lattice chain systems are determined by computer simulation. An order-disorder transition is observed in both two and three dimensions. In two dimensions the transition is second-order and critical. In three dimensions it is first-order. The entropy is obtained as a function of temperature with sufficient accuracy to test the scanning technique, a procedure devised to simulate the entropy of lattice chains. The scanning procedure cannot approximate the entropy of the systems considered here. Scanning is unreliable whenever interactions occur between parts of the system constructed at widely different times. Unfortunately, this includes all systems to which it is now being routinely applied. The problem is most severe in concentrated multiple chain systems and less so in isolated self-avoiding walks.