Abstract: This is a multi level or hierarchial memory system for a multi processing system in which two or more processing units access the memory system. This memory system has two types of memory units on each level with the exception of the lowest level. One of the types of units is called the data store and is for storing all the data at any given level of the memory. The other type of unit is called the copy back store and is for storing all the changes that have been made in data at that level either by addition or modification. The next to lowest level of the hierarchy the data store and copy back stores are embodied in magnetic disc units and the lowest level of the hierarchy the data stores are embodied in a tape unit with multiple input stations. The disc and tape units are all serially strung together on two independent accessing loops which access the tape unit through a different one of the input stations of the tape unit.

Abstract: This is a hierarchial memory system for a multi-processing system which has two or more processing units accessing the memory system. The memory system has two different types of memory units on each level. One of the types of units is called the data store (DS) and contains all the data at that level of the memory. The other type of unit is called the copy back data store (CBDS) and contains all the changes that have been made which changes data either by addition or modification and that are to be copied back to the next lower level of the memory hierarchy. The data store and the copy back data store in each level are on two different power systems and transfers of the changes to the next lower level are done in the order in which the change entered in the copy back store with the oldest entry being the first to be copied back. Each copy back data store has a capacity which is only a small portion of the data capable of being stored in the corresponding data store.