The areal density of magnetic disk is expected to grow to over 20Gb/in 2 by the end-1990s. In the INTERMAG'96, the authors demonstrated high areal density of 5Gbit/in 2 with PR4ML channel. The thermal instability can not be neglected at higher areal density than 5Gb/in 2 . It indicates the necessity to use the code which expand bit length such as (1,7) RLL code. We consider the best combination of (1,7) RLL code and a partial response channel. The partial response system of the polynomial (1+D)(1-D 2 ) called modified E 2 PR4(MEEPR4) exhibits the best performance. We performed this partial response simulation model with white noise and media - noise and examined the architectural consideration in the design of the experimental prototype.