The most common type of memory organization in promise lower cost than main memory and faster a computer system is a two-level hierarchy, consisting speed than today's bulk storage. This category of deof fast, but expensive "main memory" (e.g., magnetic vices is called fast auxiliary memory (FAM). The concore, plated wire, or semiconductor technology) and cept is not new-combinations of fast and somewhat 50 IVEI* spectrum jui,y i973