Publisher Summary This chapter describes the Alpha memory management architecture, and provides an overview of OpenVMS Alpha memory management. It describes the fundamental concepts of memory management and the architectural mechanisms. It provides an overview of OpenVMS management of virtual and physical memory. Physical memory is the real memory supplied by the hardware. A virtual memory system simulates real memory by transparently moving the contents of memory to and from block-addressable mass storage, usually disks. Virtual memory support for the OpenVMS Alpha operating system is based upon Alpha architectural features. It provides: maximum compatibility with OpenVMS VAX memory management, access to the larger Alpha address space, support for memory shared among multiple OpenVMS instances running on a Galaxy platform, and support for efficient operation of platforms with nonuniform memory access.