Figure 4: Our approximations to zone bit recording. (a): our approximation to the overall average access time under SCAN and C-SCAN. The difference between prediction and simulation is not visually discernible for either SCAN or C-SCAN. (b): our approximation to compared to simulation results under C-SCAN. Agreement is reasonable, but not as impressive as for the overall average access time. For both plots  cm,  cm,  cm/ms, and the disk spins at 7200 RPM.