This document highlights the topics required by project 2 – Research – Memory management and virtual memory for operating systems of the course of 2014. This document presents a case study by Microsoft Operating system Windows 7 64 bit Professional.2. Memory2.1 Description:Main memory is the central hub where all programs run. It consists of a large array of bytes, each with its own address. The amount of main memory is a limiting factor in a computer system, the more memory we have, the more addressable space the operating system has, increasing the number of programs that can run and the amount of information ready to be run. When instructions are ready to execute, the scheduler sends them to the CPU. This process may require more than one transition between memory and processor. The memory drive only recognizes one stream of memory addresses, it has no idea how they are generated or what their purposes are.2.2 Physical Memory: Most current operating systems today support 64-bit addressing, which includes our case study, Windows 7 x64 Professional. The hardware and software limitations of 32-bit chips, limited to a maximum of 2 GB user-addressable or 4 GB of RAM access, accelerated this transition. A 64-bit chip address space is increased to 2^64 bytes of RAM and can greatly increase system performance and the way programs can be written without having to take the above constraints into consideration. - Windows 7 Professional 64-bit has a limit of 192 GB in address space.2.3 Virtual Memory: Virtual memory is a memory management technique implemented with the help of both hardware and software. It maps the memory addresses used by a program, called a virtual address...... middle of paper ......and is assigned a three-bit age value that determines the age of a page, thus helping the operating system decides which memory page can be discarded from physical memory. The reference counter used in the aging algorithm and the way it is used ensures that pages referenced more recently, even if referenced less frequently, will have a higher priority than pages referenced more recently. refers more frequently in the past: therefore, when a page needs to be replaced, the page with the lowest counter will be chosen.3. Conclusion: Windows 7 is the first widely adopted 64-bit operating system in the Microsoft family. It fixed many security issues and significantly improved the performance and some features of its predecessors. It has matured into a stable and reliable operating system and holds the majority share being installed on the majority of personal computers worldwide.