The need for automatic storage allocation arises from desires for program modularity, machine independence, and resource sharing. Virtual memory is an elegant way of achieving these objectives. In chapter. II, two principal methods for implementing virtual memory, segmentation and paging, are compared and contrasted.
In chapter.III, based on the results of chapter.II, we consider the optimal storage allocation of pages of programs under systems and user`` budget constraints. This is one of the important problems that systems manager faces. The model presented in chapter.III, gives a strategy which operates storage systems more efficiently. An effective procedure for solving this problem and a strategy which is easy for implementing in operating systems are presented.